One of the things tropers get blasted for, for the most part rightly IMO, is that they tend to be utterly immature when it comes to talking about sexual subjects.
Until TV Tropes was forced to literally put the kibosh on this due to their advertisers, I could partially sympathize with the mass censorship, as to be honest, it definitely eliminated some genuine creepiness due to tropers who, despite the demise of the Fetish Fuel pages, just couldn't help sharing some disturbing masturbation fantasies.
However, I don't think it's impossible to talk about sexual subjects in a mature manner, and given how sex and sexuality are just as legitimate a story device as anything else, they should be discussed by tropers like anything else.
The question, however, is where to draw the line between legitimate discussion and creepy perversion.
For starters, I would have to say TV Tropes has been doing it wrong., True, having their advertisers limit the scope of what they can discuss has cut down on a lot of perverse material, but it has also limited honest discussion of sexual topics if they would anger those advertisers.
For instance, the Naughty Tentacles trope. Even when it doesn't show up as a porn device, it is often referenced and alluded to in other media that isn't straight up porn (and even some of that has a plot, thin though it might be), but as the screenshot below shows, you cannot discuss it on TV Tropes AT ALL:
In the context of whether Naughty Tentacles are your personal sexual fetish, yes, I understand not discussing it, as honestly, it is TMI to know about someone's sexual fetishes, but if it's a story element or plot device, it's a legitimate trope, and the fact you can't talk about something because a third party you have prostituted your intellectual freedom to for money limits your ability to discuss a story strikes me as cowardice.
A few other examples of tropers and sexual maturity would be the infamous "boob chart", something the SA goons have trotted out as an example of utter depravity concerning TV Tropes since day one, as displayed here:
With the exception of the very last section, which strikes me as kinda dodgy at best and pretty creepy at worst, most of the information on this chart is information about female bust sizes and their classifications in various countries and their various names in English and their Japanese romanizations, and in some narrow contexts, I could see most of this information being useful when discussing female character design or stories in which a woman's bust size is a plot element (i.e. - where a woman disguised as a man has to hide her bust size to pass as one, she uses her cleavage to hide a plot important item, etc.), and in that sense, I believe this information could be used in a mature, dispassionate manner without going into the gutter.
However, whenever someone wants to claim tropers are irreedeemable perverts, this is trotted out as "proof tropers are depraved.png" despite the fact most of it is mere information without any slant one way or another, though since I have no idea what the author's original intent was, I cannot draw conclusions on that one way or the other.
That said, the problems with tropers talking about sex mainly seems to be during the following scenarios:
1. Troper Tales/Fetish Fuel - These were just bad, bad ideas, with the latter just begging for things to turn perverted fast.
2. The TV Tropes forums - Until Google found out about it, they still had a "sex thread" (called "The Nunnery" ) in which this was discussed, and apparently until they were forced to shut it down, it was pretty skeevy. In fact, most of the sex talk on the TVT forums seems to have gone into the gutter at one point or another.
In this case, I never really thought TV Tropes should have had a full blown forum, and while All The Tropes has a forum, it's mainly limited to site related matters (no off topic, non tropes/troping stuff) because we did not want to risk falling into the gutter ourselves, and besides, if you realy need to talk about what turns you on, there are better, more discreet communities on the internet for people who really need to talk about that.
3. The TVT Trope pages: This mostly was people turning trope examples into fetish fuel repositories, and TV Tropes has mostly put the kibosh on that by banning all examples on most sex related pages. Me, I'm not sure it's a totally ideal solution (some legitimate stuff can and did get caught in the crossfire), but in fairness to them, it definitely cut down on a lot of creepy BS.
4. The TVT Work pages: Even for works that aren't outright adult, and even for some that are, some tropers apparently couldn't resist turning pages about sexual works they enjoyed into "Why This Is Great To Masturbate To.txt", something I agree is just gross and fucked up. Explaining what sex related tropes the series in question use are fine, but quit adding material about why it arouses you IMO, that's just TMI, off topic, and disgusting.
In partial fairness to TV Tropes, they did have a salutary neglect policy in their early years, back when the site was more laidback and informal, but around the time it became really popular, that's when the sheer amount of perversion the site encouraged due to the neglect became obvious, so in part, the fact there was so little attention paid towards boundaries since day one does explain why it go so bad and was hard to rein in, and the resistance they encountered to cleaning it up is somewhat understandable.
However, if you ask me, they went so far in the other direction to sanitize things that it has crippled the site mission of TV Tropes, since they are literally forbidden from maturely discussing certain sexual related topics, even if it's on mission, either due to advertisers or admin fiat.
But, since I run a site that has hopefully learned from TVT's errors and suffer none of their drawbacks like the ad money ball and chain, I think it's possible to avoid the pitfalls TVT ran into as outlined above and still be able to discuss sexual material used as tropes in media without being perverse about it.