I've covered this show a few times at work now and find that I'm completely hooked. I think it's at least as much having the right host as subject matter. I don't know where Discovery Channel finds these guys, but they've really got a knack for engaging, charismatic nerds (see also "Mythbusters")
Granted, I really didn't need to see Mike Rowe hold a cup while a pig farmer procured genetic matter from a boar, but I've yet to see a guy with as good a sense of humor about standing knee deep in raw sewage.
If I remember that the show is on, or flip by it, sometimes I'll watch it. The one where he was with the Exterminators was great, as was the Ostrich farm. I don't know how this guy manages to stay as enthusiastic as he does for these jobs :)
I was a big fan early on. And here's the but... This is the second reboot of the show. And, if the credits are representative of the show's mindset, it will more about Jen Garner in hip outfits (certainly acceptable)