I think a "college town" should be one where the college is a really significant part of the town. You can tell it is when you enter it, nearly. I don't have a specific population limit, but maybe around 100,000 at the max. Does this really mean anything? No. Columbus, OH has areas which are clearly college areas, and areas which are clearly not.
I don't think Atlanta has much of a "college area" outside the various campuses. There is a small strip near Emory which is college-y. One could live around here for ages and have no idea a large university is 2 miles distant.
I spent a few years in Chapel Hill and it struck me as "too small" to be a great college town, largeish university in a small town was not that great. There were only three student oriented bars for example. I was happy to leave. Ha.
The area around U of Cincy is "college-y", a bit, and used to not be very safe either. They could have a good CFB program IFF they could keep a good coach.