I've never heard of any of these shows.

Really? Dirty Jobs is on Discovery; the host goes all over the place showing how dirty some jobs are- stuff like pig farming, sewer cleaning, paint disposal etc.
Extreme Homes is on HGTV and is about wild architecture; they've shown tree houses that people actually live in, houses shaped like fish, etc.
Ace of Cakes is on Food Network and shows how a specialty cake business makes their custom cakes; stuff like cakes in the shape of dinosaurs, buildings, people etc.

All of them are a lot of fun to watch. :) Dirt Jobs is my fav because the host [Mike Rowe] is absolutely hilarious.