I love this one:
"4. Do they use portables or a truck mount? Insist on a good quality truck mount to be used. This is a good one especially now as even truck mount machines are so different in the quality of their performance. The truth is just like anything else…most often if something requires a larger investment it usually will be a much better asset. Some of the larger and newer truck mounts (valued at around $50,000) will out perform their smaller and older brothers by a staggering amount. A portable can never come close to a good truck mount. It’s like trying to compare a push bike to a super bike on the race track…there is just no comparison. The carpet cleaner will try and trick you into believing the portable or small truck mount is just as good but it just is NOT."