I would say it's not that you especially attract these sleazy men, it's just that there are a lot of them out there percentage-wise, and not a lot of the decent kind!
Also, I've read that men today in general seem to think they have a lot more women to choose from, that women met online are somewhat disposable - the flick right mentality makes it seem like they shopping for women in a catalogue.
So they take stupid chances they wouldn't usually take, because they figure if you don't respond, there will be someone else who will. And there's no repercussions for them - they won't be running into you at work or around the neighbourhood later.
It's sad, but it seems to be the case for most men online. Respect for women is not a priority for them - and with no consequences for bad behaviour, they just let loose.