Hello FightGirl ..
Understand what you mean .. trying to have fun while others just look to cause probs. Maybe you are not hair color or bodystyle they prefer. So instead of moving on, they leave some garbage post.... that does nothing for no one.
Blocking.. IN open forum, think that is a no, anyone can post in, to threads. You may be able to complain or report it to mods, if offensive, vulgar or maybe just mean spirited, to personal. They can remove it, if it looks truly against regs, rules or simply being indecent. Some of the guys can get crude and overly suggestive in posts to or about the ladies..
YOUR personal profile... Not sure if you can after you create it.. Mods would have to answer or direct you. YET you CAN block posts to your profile or photos. Making it so ONLY people on your buddy list, can post comments there. Have to modify your profile.
May be something to look into, hope this helps.
Storm