In my line of work (I prefer not to really talk too much about my job or employer online, sorry; if anyone actually cares, hah

), I get to talk to the people conned by these guys almost weekly. Just today I ran into a guy who'd bought a "Dahlton" surround sound system out of a van.
Honestly, a large number of the people seem completely happy with the speakers and think they're just as high-end as the price on the box (yes, seriously, they print it on the box fairly regularly; along with the rest of the inane "Digital Speaker" nonsense).
I've noticed a large number of the people say the speaker-scam salesmen approached them at a Walmart in particular. I'm not sure if it's statistically significant, but that might be where to hang-out to run into them. I have a bit of a personal boycott against Walmart (among other stores), so that might be why I've never been lucky enough to run into these folks.
The brands you'll find seem region-dependent. I've seen Audiofile, MTS, Digital Research, and Digital Pro Audio fairly regularly. Today was the first time I'd run into Dahlton. I've never seen Dogg Digital or some of the other more ridiculous sounding ones that get mentioned online. They all seem to be built in much the same fashion (look at the wood speaker grills on many of them, for instance). This is nearby Denver, Colorado for what it's worth.