In many of the online communities we writer types frequent, our clients pop in to post jobs and find workers. A lot of people seem to forget this, because many writer forums are littered with complaints about clients or contributions that may be less than professional. In forums that are open to search engines, clients may find the site by seeing posts about their company in Google.
Slamming other writers will reflect very poorly on a writer, and if a potential client sees that kind of behavior, it may spell the end of a potentially profitable gig. If you talk poorly about a client, you may also be putting yourself at risk of legal action for defamation, which can have disastrous results if you have to go to court.
No matter what website you frequent, if your business is tied to your identity there, you should take care to be sure that the things you say and do on that website reflect positively on you, not only as a person, but also as a business.