I guess it would depend on how you would define that "idea". Is it a generally good idea without any details? (i.e. create a better search engine then Google) It's a good idea but worthless if you don't have the details and any good algorithms behind it. Another point is that ideas develop from previous thoughts and ideas. there is metamorphism about them. And if you also add natural selection to it, for example to your auction site idea, then it could make it work better. but then of course, sometimes it is the unpopular idea that really works and worth something not what gets the most votes. Certainly true when you look at science's history. Yet another important part of an idea is its timing. many examples for this... but just to give one, sending dvd rentals by mail (Netflix) Good for now but perhaps will be over soon and sound ridiculous when more people get high speed internet and can stream.
anyway there are lots of things to conceder about an idea before declaring it worthless or not. And I would definitely not narrow it down to idea vs. execution.
anyway there are lots of things to conceder about an idea before declaring it worthless or not. And I would definitely not narrow it down to idea vs. execution.