Jeremy Zawodny posted a request for help on picking a steam cleaner.

One of the responses mentioned the Bissell Spotlifter. I've tried this, being something of an expert on steam cleaning lately. As a tool, it has a very narrow opening...allegedly you have to sprary the solution out the front, and then hold the machine at a 45 degree angle to get the suction going. It's very difficult to tell if you're getting the fluid back off the carpet at that point in time, so you're left to ponder whether the stain is going up.

Unfortunately, touching the area on the floor covered in whatever substance you don't want to go near, seems to be the way to evaluate if it's working. You also need to apply substantial pressure to feel as if it's working.
Add to this, the fact that carpet fibers tend to get in it, and gunk up the works. To be fair, it's really easy to pull the brush section out, but your fingers must then untangle the fibers, which are, again, covered in something disgusting you don't want on you.

The one spot where the Bissell is really helpful, is the sides of stairs. You can actually steam clean a vertical surface, which is close to impossible with any of the full size power steamers.