There is an old and unfashionable notion, mostly abandoned by big-time basketball in this era of glass practice facilities and player lounges built like hotel suites, that a young man learns his trade best from a master who tells him the truth rather than one who tells him what he wants to hear. The old trade guilds ran on that principle for centuries; an apprentice endured the master's unsparing eye in exchange for a craft that would outlast fashion. Kelvin Sampson has been running something close to a guild out of Houston for the better part of two decades, and he has never once bothered to…