I donā??t know about the facts, but I can only go based on my own experiences. Some people say that people canā??t build up a tolerance to weed, but I doubt many people experience the same effects every time they smoke as they did their first time. Iā??m sure that at least a big part of weed tolerance is in peopleā??s minds, but being that this is a drug that affects the mind, that isnā??t necessarily insignificant. I donā??t mind having a tolerance built up really. For me at least, once Iā??ve built up a tolerance, all the stuff like getting the munchies and red eyes go away.

Here is a thread you might find interesting:
http://boards.cannabis.com/showthread.php?t=28005