I've only saw one magician perform with a "full" coke bottle. My wife also saw it, and after the show told me that it looked very fake as the liquid didn't move. That was one of the biggest reasons why I never purchased that particular bottle. So I honestly would suggest getting an empty bottle instead.
thank you for putting the perspective into a spectator in the audience. i knew few people would be able to make the assumption that the bottle is fake just by the way the liquid doesn't move, as you already said. i am going to look into buying an empty because it will eliminate the speculation of the "non-moving liquid".
once again, thanks.
if anybody else has some input or thoughts about the subject, please post!