The bad ones will kind of just do the same exact routine every time you go there and they'll do the same thing to everyone that goes there -- wham, bam, ty ma'am style -- get you in and out the door as quick as possible! They'll probably pop just about everything they can, which accomplishes not much of anything at all. I guess you'd call that the bruteforce method of chiropracty?
However, a single bad adjustment can painfully linger for weeks.
A good chiropractor for me was Dr. Blake Meyer at DSMCore. He would take a whole half hour and do some targeted deep tissue glute massage and nerve flossing that really helped my sciatica. Then finish up with a few minor adjustments and send me on my way, walking a little taller and straighter and with appreciably less sciatic pain. But don't expect miracles.
I tried a physical therapist near his office but she pushed me too far, too quick and made it worse. So I just stuck with Bob(RIP) and Brad on YouTube and did it at my own pace.