I would say "terrible at best" is a extremely broad generalization with no real basis in fact.
Can build quality be suspect from time to time? Yup
Are Gibson basses boring? Yup
Are Gibson basses overpriced for what you get? Yup
Are Gibson basses versatile? Nope
Totally just my opinion, but I have owned 4 Gibson basses and sold my 3 month old SG reissue last month as it was just collecting dust.
Gibson basses in general are great for older rock like the Stones, but they do not give you the tonal range of an EBMM, Lakland, Fender Jazz, etc, etc, etc.
BUT... If you can find a good used Les Paul Standard.. that is a nice bass. Expensive ($1500+) but something you may get more use out of depending on what you play music-wise.
Try before you buy is very important with Gibsons. My SG was as good as my Sadowskys as far as fit and finish went, but I have played a few that were amazingly poorly put together.