I will say it depends. How big? How many? What information can you get about when it was repaired, how bad it was before and who did the job.
I for one would not automatically run away from a boat with blisters, but I would expect to get the whole story and talk to the people who did the work. I would also expect to have the current blisters evaluated. And of course I would expect to get a good deal on the boat.
Blisters won't sink a boat and most boats in that era had blister problems. So I would check it out if you like the boat, but be very very critical.