PETA, in my mind, is not truly an animal rights group. Rather, they do a very real and very active harm to the cause-- they make it look ridiculous. Their antics turn off people who might otherwise be very sympathetic to such a basic thing as treating animals with respect.
Every time PETA throws red paint on someone wearing fur, that's one more person who will always associate the animal-rights movement, including legitimate groups like the ASPCA, with nutjobs and lunatics. People who might otherwise have been potential volunteers become enemies instead.
So way to go PETA. You do harm to animals.