Putting aside forums like this one, why would players have official forums if they don't see what their own fans write from time to time? Forums like Henman's, Federer's and Mauresmo's have question and answer sessions from registered members. I'm registered to Mauresmo's site and have sent questions.
Much lower ranked players may have some sort of outlet. 1984 Wimbledon finalist Chris Lewis contributed to a forum recently in response to something he had read. That was well documented.