Exactly!
The key to finding truly great deals is to know what you like and what might be worth flipping, then go out with an open mind.
The great bike deals can often be on bikes you've never heard of, but the opportunistic (in a good way) side of you can present buying opportunities that are far better than buying anything as "what you want, when you want it".
A local charity thrift store put a donated Miyata 1000 out behind their strip mall store with a "free" sign on it. There were two bikes actually, I've forgotten what the other one was.
And when the local Goodwill store put a weathered Windsor Profesional in their dumpster, I just happened to be riding by and spotted what looked like a Campagnolo Record crankset (it's always the high-end crankset that catches my eye when I find something like a free PX10 or Centurion Pro-Tour in the trash).
Then there was the time that my friend spotted a 1997 Lincoln Town Car with a "free" sign on it; all it needed was a new intake manifold, tires, battery, alternator, a few power window motors and lots of cleaning:
