I felt that the Prochem thread that Ian has referred to was quite offensive.
We had a poster who said something along the lines of: I sell prochem products, come and buy them off me. This forum is not about blatant advertising and self promotion, it's about sharing knowledge and experiences. Yes, the site owner is a supplier, but Mike doesn't come on with a BUY, BUY, BUY message, just a discreet advert and the occasional promotion. If someone posts that supplier XYZ is offering good service/deals, then to me, that is a different issue and is acceptable. Obviously, it usually is to Mike too.
So please, be respectful to the person who "put his money where his mouth is" and supplies us with the opportunity to communicate on a global scale and without charge!
Safe and happy cleaning

Ken