I tried one massage studio there a couple years ago, but it was completely legit. I wish I could remember the name of it. Sorry.
The strip joints can be pretty fun, though, what with Iowa being full contact. Beach Girls was a bit out of the way and a bit of a dive but still pretty good. Big Earl's way too much money (first time though, I probably misread some cues). Touch of Mink (Minx?) was hit or miss, depending on the dancer.
You can find listings for these places in Midwest Nights, a strip club rag you can find at the Love Doctor and Sex World.