The best part of advertising on TV is that there is a market for almost any product or service, you just need to know how to reach it.

Whether you are selling paint thinner, a circular saw, door stop, or block of cheese, with proper marketing it will sell.  Look at the Chia Pet concept.  Who was the guy that said, okay, lets have a piece of pottery shaped like a dog that grows grass for fur.  One television commercial, and the product is one of the most successful novelty items on the market.

What are they keys to successful advertising?  Obviously, you have to have a commercial that doesn't make your viewers want to change the channel.  Also, you need to think of who your market is.  For example, lets say you are the guy I was discussing earlier who is selling the block of cheese.  Think to yourself who is going to be interested in good cheese.  What time of day?  What channels?  What show?  Well, obviously it doesn't take an expert to figure out that a cooking or food based channel might be a good place to start.  Perhaps a show that deals with low-carb food might be a more specific area to look at.  Time of day, is fairly irrelevant here so any time would do.  If you are selling the circular saw, try Home and Garden shows and channels or do-it-yourself shows. 

Really, the possibilities of TV are endless.  Don't get discouraged if your commercial doesn't place itself so easily.  Talk to the people at the production company you are dealing with and they can help you find out where and how to advertise.