They are just card they hand out!! With girls on the front and they are advertising coming over to your place/hotel and doing very sexxxy strip shows or escort services.. Its kind a scam, it will say specials for $79 bucks but when they get to your hotel they said oh no its $200 in hour and escorting is $300-$500, it says $79-$100 cheap to get you call.. If you really want to know where the girls are you ask a cabbie and they for sure will hook you up with better deals and no BS.
They are information, many representing on call escorts though prostitution is illegal. They cannot be stopped due to freedom of speech issues. Visitors, like locals, just need to say NO, ignore them, keep walking.
They re aggrevating. People just end up throwing them away and they are thrown all over the sidewalks. Disgusting.