Right, sorry I wasn't clear, I was only using their more recent adwords success (or lack thereof) now to extrapolate what their success would be on "buying a small amount of adwords and using a fake signup page to test a need, before the product even exists.".

If adwords isn't so good for them now that they have a fully functioning product and well known brand, can you image how much less successful running an adwords campaign would have been for them 3-4 years ago before Basecamp even existed.

It would have probably sucked, and if Jason only listened to this hypothetical adwords datapoint would he have said, "you know what, our adwords account isn't driving anyone to our fake signup page, we better not build Basecamp"?