Also,a lot of times,the higher the fat content is of the rib,the faster it might end up being just right even if it is falling off the bone.
Melted fat makes the meat not stay on the bone sometimes,as posted above about drying out etc.
Fatty racks can be abused more.
I buy a lot,if not most stuff on sale.
That sometimes/most times means poor/less desirable cuts,or stuff people won't pay regular price for.
Sometimes the rub makes a difference too.
I like rubbing beef ribs down up to 24hrs before and pork about 8-10hrs.
Cold smoke only over wood.
Usually Hickory and Scrub Oak.
As posted above,Technique and other things (the old lady IS always right...)quality of the rack etc. all have a bearing on the final product.
I find Pork baby backs are easier to overcook.
I usually go for Country style myself-IF on sale.
The right amount of fat and meat.
GREAT for grinding into sausage too.
http://www.porkbeinspired.com/Cut_Country-StyleRibs.aspx
Ready for an overnight sleep,then a cold smoke...