Nice guys are often terrified of being labelled as "pervs" or "creeps" by women.
The important thing to realize is that this label is easily thrown around for no particular reason.
If you look at a woman and she finds you attractive, you're not a perv.
If you look at a woman and she thinks you look nervous or looks like you're "below her" value, then you may suddenly become a perv in her eyes.
It says nothing about your intent. The attractive guy could be a rapist, and the "perv" could be a serious romantic who has nothing but her best interests at heart.
Stop worrying about it, and realize that being called a perv just means she's noticed you, and "something" was a bit off. It's not your problem, other than to the extent it gives you something to aim to figure out how to improve. (But be careful! Make sure you figure out the real cause she took offense, which can, but doesn't have to be, different from what she says and believes is the reason).
While learning to calibrate, you might want to be a bit careful with girls in your social circle, that is all, as that's the one area where this might haunt you in the form of a negative reputation.
(That's not to say there aren't behaviours that "legitimately" put you in the perv/creep/distgusting excuse for a man category. Don't use this as an excuse to act like an asshole.)
When a woman puts an ad on a dating site and asks for "no pervs" it does not mean she won't talk sex or won't get laid. It means she won't talk sex to a guy that is needy and pushy and goes straight to the point before making her attracted. It means she knows that the guys she'd want to have sex with are smart enough to realize that they can get her by playing things a bit more cool and get to know here at least a little bit before whipping out their dick.
When a woman says in a chatroom she doesn't want to talk to pervs, it means the same thing.
Some of my nastiest conversations (and dates) ever have been with women who insisted they did not want to talk to pervs and did not want to talk dirty. So I talked to them normally, and just steered the conversation towards attraction and indirectly to sex, and soon they were leading the conversation towards kinks I'd never have considered bringing up.
The irony is that being very direct and sexual can work (if confident and well calibrated) extremely well in situations where most guy would never dare to, but will rarely work in situations where the barrier is low, because a low barrier (such as being online and anonymous) brings out all the insecure little boys.
Incidentally a way of turning these more "innocent" conversations sexual is to talk to her about how many pervs approach her, and show her you understand that she is getting hounded for sex all the time, and sympathize with her about how those guys are a bit sad. You create common ground, set yourself apart, show social intelligence and get to talk to her about sex as her attraction for you is growing.
This is key to understanding a lot about female demeanor. Almost every restriction she states is contingent on something, especially on trust, attraction and emotions.
If she trusts you and/or is attracted to you, and you make her feel good about you, herself and the whole situation, a whole boatload of rules goes out the window, and you need to recognize this.
Behaviour she talks derisively about when applied to someone she does not know all that well is suddenly a massive turnon when she trusts someone to not blab his mouth about it and she trusts that he is not only after her for sex or at least is connecting with her on an emotional level.
As an example, I once spoke to a girl that insisted she didn't want to talk about sex. But once we'd spoken about the above for a bit, she started warming to me, and started confessing all kinds of things. She turned out to be quite the kinky little minx...
She admitted to being a submissive (don't confuse sexual submission with someone who'll roll over in daily life - the two can coexist, but don't have to), told me she got really turned on by being "sexually available" whenever her man wanted her to. This was part of the reason for her caution - most men would take that kind of submission as a sign she'd be "easy" and that they didn't need to put in any effort. But being submissive and available to a romantic partner is of course vastly different from jumping into bed with just anyone.
Having her man just coming up behind her and pushing her down, for example, was a large part of her fantasies. She admitted she found it a particularly big turn on to be dominated by a white man (she is black), which would've attracted a whole different set of morons (of both races) if she'd admitted to it early in conversations.
All of this came largely unprompted. Then she told me she was wet.
So much for not wanting to talk about sex. The key was that I just set the stage where she felt comfortable drifting closer and closer to it, and before she knew it she brought it up. She could hardly accuse me of being a perv when she was the one bringing up the kinky stuff... In fact, I kept playfully pretending to be all innocent, in a way that made it very obvious I liked where she was going, but that made her be the one pursuing it.
Create a role for someone, and let them fall into it, and they will keep it up, because consistency with past actions is a major psychological driver for most people.