Always work under the assumption that things are too good to be true on TV and that salespeople are manipulative. Do you own independent research, like on the internet.
Well just think about it as a scam. It really is a scam. Just don't watch the shopping channel at all. It's easy to avoid watching that channel if you fall victim to it.
I don't have trouble with modern manipulation techniques. I watch tv and listen to sales people but I already know what I want and need and no one sways me.
I think the best thing to do is to learn as much as you can about how commercials and sales people manipulate people into buying things. That way you'll recognize it when they're trying it on you and it'll be much less effective.