My experience with dating websites was much the same as yours, with men and women, unfortunately.

I learned, after awhile, that some sites are better than others. For example, the ones that cost money usually have people who are more interested in relationships and not flings. I know not everyone can afford that kind of thing, tho, I sure couldn't.

So I looked at the wording I had in my profile. I had to get more stern or strict about certain things. I made it clear that pictures of that sort would result in immediate end of conversation, no explanation. I put in my profile that I was only looking for a relationship that could turn into something serious eventually. I also changed what I was looking for to "long term relationship," not friends or short term or any of the other descriptions.

For me, those changes weeded out some of the pervs, but not all.

Also, I am like you in the sense of being open talking about sex and topics like that. But I had to set boundaries from the beginning, because of my past. I knew if I hadn't said it up front, that I could falter on my boundaries at some point. I had to remind myself that I am worth a partner who will respect me and my boundaries from the beginning. Talking or texting about sex or topics similar is one thing, for me, but the pictures cross the line. Also, if the greeting is a comment simply on my appearance or what they would like to do, they have earned a block before even a response. Simple as that.