'Legitimate' in this context is not intended to be synonymous with 'raking in cash'. I'm talking about profitable businesses with sustainable revenue models - not someone with a niche, keyword specific domain they registered three months ago that's benefiting from some temporary adsense luck.

My business partner and I sold a business a couple of years ago because our hearts just weren't in it anymore. It was profitable, but not enough to offset the pain in the ass of running it. We sold it to a group with a collection of complimentary businesses, and they've had great luck with it.