They may not build the highest quality stuff. They may do some hokey stuff. There may be some ridiculous antics they do. They may have attitudes. Personally, I still watch it and find it enjoyable for the most part because it's about GUNS! I'd much rather waste 30min out of my day watching this than so many of the other crappy tv shows on currently. It could be better, but at least it's about guns.
Ummmm....Mythbusters uses the same disclaimer. Given the crop of idiots in the world today (and the scum-suckin' attorneys willin' ta represent 'em), they HAVE to say it.