TellyBetting has only been around for a few years and is increasing in traction at quite a rate. However, I have noticed a certain snobbery amongst some sports gamblers to us young bucks. They think it is rigged and ridiculous to bet on something as unpredictable as TV shows. I also get some incredulous looks when I tell non-gamblers what I bet on (they tend to come round when I tell them what I win).
I would say that most of us take this into account when betting and enjoy the rollercoaster nature of it. I would also say that it is more trustworthy than the horses or dogs. Like the horses, there are patterns which are identifiable and can be used to make money.
There are lots of shows as well to try, it does help if you find one you like - Strictly Come Dancing is a good one for many.
So, give it a go. You may like it.