I mean all of us know it to some extent, but the true extent of it really shocks me. Basically, most pros use racquets NOTHING like the racquets they endorse, and most of them are postly paint jobs. I learnt from a source that the pros actually have specially made frames that are made only in some place in Austria, and that the frames are not even customized from the frames that are sold in stores; they are completely different. For example, Nadal still uses the first generation Aeropro racquets. What happeens is most players only just get the paint job, but if you look closely you can see that the frames are totally different e.g. Murray's radical pro is completely different from the one sold in stores.
I don't think Murray even uses a Radical. Most of the players with Head use a customised version of the Pro Tour (which isn't sold any more).