Craigslist blues in 2019? It is going to get a lot worse.
From the late 80s for a period of 10 years, road bikes were dead dead dead. During that period the industry was pushing mountain bikes - hard, for all forms of riding. By the early 90's most decent mountain bikes had suspension forks, and later in the decade, full suspension was common. You could not give a road bike away during the 90s.
So this vast wave of 'mountain' bikes now is ubiquitous in the second-hand market, compete with blown irreplacable suspension forks, wobbly, worn out suspension pivots, and slow heavy knobby tires on 26" rims which nobody wants any more. Basically these bikes are terrible all-round bikes for general riding; always were, but they were marketed hard.
We see this at our local bike Co-op: 3/4 of the recent donations are useless old MTBs, in which replacing the suspension fork will cost more than the ultimate value of the bike.
At least the 80's era MTB's were of a somewhat decent quality. If you retrofit a cost-effective rigid fork, and install slick tires, these bikes are great all-rounders.
The next phase of C&V will get even worse, as the cheap department store MTBs that followed the initial phase of the MTB domination will flood the second-hand market. These bikes are even worse, as they feature the cheapest possible components, as manufacturers struggled to crank out $200 bikes complete, but now had to factor in the extra cost of suspension forks and rear ends.