Is it good or bad to pop pimples and/blackheads?

Probably not: A good idea as the bacteria can spread and cause further infection and the trauma can cause scarring. Gentle pressure on a blackhead , especially if using retin a (tretinoin) or equivalent medication is probably alright if using tissue between the fingers and very light pressure to avoid trauma and scarring. Ith wise, have them extracted by a professional.

Pop: Gentle pressure with a warm towel for those pimple with a "head" may be tried. Better to see a dermatologist for prescription antibacterials, oral or topical retinoids , oral antibiotics , etc. Large, tender, red cysts may be injected with corticosteroid.