it's usually the older, washed-n-worn quite a bit, or the lighter weight shorts that get sheer. Stick with 6-8 oz shorts, they're much denser.
and I wear mine au naturale too, I don't use Chamois Creme and I've never had problems except with cheap shorts.
Right now I"m wearing Sugoi (which I just tried for the first time and LOVE), Performance Centurys and I've got some Terrys to try.
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"