There's blisters, and then there's blisters. Some are merely cosmetic dimples under the gel-coat and others are rotten to the core (so to speak). I'd run screaming from a boat the surveyor recommended a full-blown peel job, but a few (50 or less) SMALL dime or nickel sized blisters on a 20 year old boat are not a deal breaker (for me, anyway). As long as the underlying hull is sound it's a half-day to "zing" them with a grinder, time to let the spots dry (non-sailing months - we have five of those up north) and then a half day to fair in with epoxy resin.
If you find blisters on a 3 or 4 year old boat - that's a bad sign.
Here's a report written by someone not trying to sell you a "peel"
Reparing & Preventing Blisters