Thanks for the replies. So certified pre-owned actually means something?
As someone who used to work at a manufacturer dealership, yes they do mean something. To be a certified pre-owned, it has to meet many criteria specified through the manufacturer, which is why those cars will also sometimes have a real warranty. Of course that means you also pay a premium, because you're guaranteed that service has been done and everything checks out. On a normal used car on the lot, even at a proper dealership, sometimes things like brakes don't get done if its determined not worth doing and they have enough life left where they will last until next year or something. Same with other services that might not be due, but will need to be done soon. Those things get done on a certified used car.
One reason I don't trust many of those used car only lots, is because not only have I interacted with people who work there and realized they know nothing. But when a proper dealership gets trade-ins, if they're not worth fixing to put on the lot they end up going to auction. Those cars are then purchased by those used car dealers because they can get away with not fixing issues and therefore making a profit. You wouldn't believe the number of times I recognize cars that we rejected and sent to auction, which later come in for service months later where the new owner is angry that it needs so much work done because they got shafted at a shady dealer.
I would honestly trust a car off craigslist more than I would from a used car dealer.