It's been a decade since I've had a problem with a buggy footprint from a default library (contrasted with quite a few buggy footprints I made myself). But just two weeks ago I had a board problem because my selected LED had a slightly different leadframe and pad geometry than the library version. (A '3030' package, comparable to offerings from Cree and Lite-on and Lumileds and - I thought - my LCSC-sourced Everbright.) The stock library footprint was produced in 2016 for a nominally equivalent package from a different manufacturer. When I used one part number in Kicad and bought a different part number, it's obviously my fault. If I worked at a company of scale instead of a company of 20 I'd not be selecting random LCSC part numbers, but that's more so that they'd be confident in their ability to actually buy the thing than because they distrust the stock libraries.

There are too many low quality and duplicate models in the standard library.