Ask for proof of monthly revenue for the last year. However, I think you would derive more satisfaction if you bought the domain and built it yourself. It might be cheaper also. Depending on your plans.
Garbage, yes.
"Developed to be flipped" nonsense, sometimes even less.
From time to time, you can find a credible, durable income stream being sold off and on the basis of garbage-overload, it gets dragged down and undervalued but for the most part, correct. 12-24 months is the 'gamble' current multiple dice rollers are willing to take that garbage will remain floating on Google for just that long to hopefully recoup their investment only to dump it off on the next sucker, which makes up their "profit" (then with the added advantage of it being "aged" another two years and appearing even more credible to the next batch of morons!!!).