If you say "I 've a server it costs x contact me" it is obvious advertising.
If you say "PM me" I take it as you are saying I Have a server, contact me.
If you are in the anyone recommend a server thread, the only posts allowed are requests, all answers should be by PM.
If you are in a thread and say something along the lines of "my customers never have any freezing" again it is a way of saying I have a server.
I hope this helps you out.