I would say try two or three different RCs every time, and if all give positives, try them again, especially if you really suspect you might be dreaming.

RC always work fine to me, and yet, one of my last times I turned lucid from RC, I did the hand check one and I got two false positives, but something (can't remember, its somewhere in my DJ) was so nonsense that I knew I was dreaming and after the third try, my hands looked weird... so just try the same one 2-3 times in a row and/or switch around.