Complicated issue
Should you be concerned? Absolutely. What to do? That is a complicated answer. Blistering is a highly debatable subject. It sounds like you have a lot of blistering. You can have gel coat layer problems, and/or deeper problems that extend into the laminate. The latter can lead to more serious trouble over time. It sounds like this has been going on a long time.You can do many things to repair, from grinding out and resealing individual blisters each year, to peeling the whole hull and putting on a barrier coat. You may be ready for the latter.If you haven't already, get a professional opinion or two. The full fix is expensive. Don't let anyone tell you this isn't a real issue, it indicates water intrusion into your hull, with possible delamination. And even if its just cosmetic, racers will tell you that those bumps will cost you some real speed - something consider if you race, or if you plan to cruise long distances. (You'd be suprised what an extra 1/2-1 knot will get you on an all day cruise).I hope you are still in negotiations for the boat. (BTW a full peel, dry, barrier coat, and repaint can cost $6-10K depending on where you get it done). Let us know what happens-