Hm. Trash has a dozen meanings. I guess I would say, its trash in the use-once, disposable sense. Nobody thinks their ad is going to be timeless.
However, what about Apple's 1984 ad? Or the BMW mini-movie advertisements they ran about 6 years ago?
There are some incredibly cool concept ads out there. They usually are not the ones broadcast, but if you watch the end of the year awards for the industry, there are some very creative minds working there. (And creating some impressive work).