by the time a guitar track is recorded through several mic/amp combinations, run through a variety of studio effects and then mixed and mastered, it would be nigh on impossible to tell the difference, particularly if the engineer/producer didn't want you to.

as andrew said, most punters couldn't tell the difference. however, i think the player can. a tube amp reacts differently to a solid state, and i know thats one of the reasons i use one. i feel it helps me play better, and that is something the punters can pick up on...