Advertising via Magnets

I know you don't see them much anyone, but is it worth doing advertising on magnets?



I understand some business like plumbing would do better with this type of advertising, but I'm wondering if it can be used for everyone?



They do say "any advertising is good advertising", or is this really just a waste of money, and I should look at other things.



A newbie really looking for advise on this one.



TIA