I thought this was an old argument, but apparently I was wrong. I still hear about it when I'm on forums, both within and outside of DA.
So, according to both slash/het fans and non slash/het fans, there are two different types of Megatrons. There is the Perv Megatron and the "real" Megatron. From what I've been seeing and hearing, I think this probably applies to the Transformers Animated series more than the other TF Universes.
Anyway, when my friends ask me about this argument, I have trouble answering because I have mixed feelings on the issue. Unless you haven't seen my works or some of the TF art I've faved, then you would know I'm a slash/yaoi/boysLOVE fan and Megatron is no exception. Still, I have probably a different viewpoint on the argument then most would guess. Hopefully in this mini-essay, I can explain my view.
To those who are "anti-Perv Megs," I actually agree with you to a certain degree. I actually don't care or even like the "Megatron the Perv" concept at all. I think it destroys his image completely. The Megatron I grew up to love and adore would rather beat Optimus to scrap instead of steal his panties, which robots do not have. I love AutobotV's work - I watch her on DA and she's one of my favorite authors on FanFiction - but I have to strongly disagree with her "Megatron the Perv" series because I highly doubt Megatron is even REMOTELY interested in any bot's non-existent underwear.
Now, as a slasher, I do pair Megatron (any universe) with other male canon characters, but I try to keep him in character as much as possible. For example, I never make him the bottom EVER, with the exception of Lugnut, but that's only because I feel as though Megatron would only ever interface with him if Lugnut were to lose it and rape him. Also, making him bottom for me makes him very OOC. This is Megatron we're talking about, the evil and brutal tyrant that has killed hundreds maybe more like thousands of Cybertronians with his bare servos. I highly doubt he would bottom for anyone. He has WAY too much power and pride to be the uke. PERIOD.
Now, onto what I suppose are the most controversial pairings - Megatron/Starscream and Megatron/Optimus - which are probably two of the most popular slash pairings.
Let's start with Megatron/Starscream relationship. Both make valuable arguments and I will present both in summarized versions.
The anti-slash argument states this: "Megatron hates Starscream and vice versa, and the tyrant only keeps him as his second command to keep an optic on him so he can't do anything to overthrow him." Well, it's an obvious "DERP!" that the two hate each other. Also, that is true with the whole saying "keep your friends close, but your enemies closer." Now, just speaking G1 here, killing Starscream would most likely have the other seekers - mainly Skywarp and Thundercracker - put him on their hit list. Those three are basically like family, both in fangirl and canon perspective. I highly doubt Megatron wants to lose some of his best air warriors.
The slash argument states this: "Megatron has interesting wordplay with the seeker and if he really wanted to stop him from trying to overpower him, he'd just kill him. But come on - the seeker's still alive after how many threats?!" It is true with the word play; if you listen to what they say to each other and you were to say it yourself with someone else, you can find the innuendos with the lines. Again, speaking for Animated series this time, Starscream's "family" didn't show up until Season 2 and unlike G1, they didn't really have each other's back, so to speak. So, with that being said, yes - it IS a wonder on why Megatron would keep the seeker alive when I'm pretty sure he has other soldiers at hand to be Air Commander. Shockwave would probably make a better SIC than Starscream anyway.
Now, as for my position on this pairing
I don't mind either way. I like both fluff and angst in terms of slash. In the end though, I actually prefer Megatron beating the living shit out of him rather than him "making love" to him, only because I find it when Starscream fails quite amusing, especially in the G1 series. I do write about this pairing and I did make a story about them involving krazifreak's Kittycon concept, but that was an AU. If I were to ever write a fic about them in another universe like Armada or Animated (which I probably will one day), if there is any "slash" to it, it will probably be about how much Starscream hates Megatron because of what he does to him in addition to beating him. I find if Megatron does interface with him, it's more so to humiliate him and degrade him more so than it is because he desires the seeker or because he needs to relieve himself.
The other slash pairing, which is my OTP, is Megatron/Optimus. Now for me, the slash argument is this: "In TFA, Megatron should and could easily overpower little ol' Prime, but it always seems that he fails. In all of the other series, their word play is just too damn hot and steamy to ignore."
The non-slash argument is sweet and simple: "the two of them are ENEMIES and Optimus is with Elita-1, for Primus's sake!"
To address the non-slash argument, I totally see what you're saying. They are enemies and Elita-1 is indeed his mate. Well for me, I don't like Elita and as for being enemies, they remind me of Megatron and Starscream I love their wordplay, both as enemies and as mates (obviously the mate is the slasher's perspective, but you get my drift). I find Megatron obsessed with killing Optimus, just like the Joker is about killing Batman it's unhealthy and creepy. Megatron always seems to be dead-set on getting Prime alone and off-lining him for good. Now, as a slasher, I find Megatron wanting to make Optimus suffer before death and what better way do that than with forced interfacing? Also, Megatron and Optimus seem to get along all right once they have a common enemy. That there is like a red flag to slash fans like myself, making me through in the word "love" into their relationship. Again, I like both fluff and angst in regards to this pairing. However, I still refuse to believe that Megatron is out to rape Optimus and steal his panties. No.
Now, some anti-perv people argue that Megatron isn't even remotely interested in even having mate. I have to disagree with this, but only because I highly doubt Megatron was the way he is now. I'm even writing about it in a TFA fic where he had a mate when the war first started to back up my view. People aren't born to behave like tyrants they're made into ones.
Slashers like to argue than it's FAN art/fiction. It's what they want to happen. Hate to burst the fun fan bubble, but no matter how much the term FAN means, you still have to abide by the rules of whatever fandom you're writing about. Even if you make an AU, you still have to be true to the character's personalities, otherwise it's just insulting. They also argue that Megatron's voice adds to his perv charm. While I must agree that Megatron's voice in TFA is VERY orgasmic, I don't think it attributes to him being a pervert.
All in all, my point of is that in this particular topic on the left-wing Perv supporters and the right-wing Tyrant supporters, I'm pretty moderate leaning more right than left. I am ALL for the tyrannical Megatron because he is just awesome that way, but I don't mind him being a bit ecchi, but only in the sense of angst or fluff. I'm not for him being perverted and stalking bots to rape them.