An endorsement is simply an advertisement for a particular brand, nothing more. They receive benefits just as a dealer would so why do you think that an endorsement lends credibility to any brand? I was lucky to meet a couple of band members in the band of a very famous trumpet player who endorses a particular brand of mouthpiece, when I asked them why they chose that mouthpiece the answer was "because we get them for free". I personally am more interested in how a horn plays than which big name plays it. It doesn't matter if you play a Winston or a Monette. The most important thing about any instrument is the sound you make on it NOT the sound other people make about it.