If you change you account settings so that only people who you follow can message you, this helps. And only follow back women. Most of the men on here are thirsty creeps. They follow young, pretty girls like you and I for a reason.

That this sort of thing happens really bothers me. Perhaps, since there is a rating system for teachers, there could also be a rating system for language partners. Nothing complicated, just a "I had a session with this person and they didn't do anything inappropriate". I don't know, it is just an idea.

And that's why it's so difficult for decent guys to find studying partners. I guess there is an option to block such users, just block them and keep learning.

My guess has been that there is a small group of guys who are doing this. Most likely they are repeat offenders. Please report them.

You can report those guys to italki and then block them. Go to their user profile and on the left under their picture select "report concern". After you've reported them, choose "block".