I would start here:
http://www.catalina28.net/ at the C-28 association site. Every boat has its merits and its foibles. I STRONGLY suggest buying the boat that speaks to YOU (and your partner, if you have one). What others have to say is often comforting, but they will not live/sail/sleep/eat on the boat, make the payments, or deal with all the maintenance and upkeep issues you, the eventual owner WILL. Take opinions with a grain of salt. I.e. trust your gut, and get facts.
I would suggest:
1) get some sailing and motoring time on the boat/model in question
2) look at the boat with an eye toward how YOU will use it. Cruising? Day sailing? Racing?
3) analyze things like storage, seating, sleeping, privacy, cooking, head sitting, showering, entertaining, and whether the boat is adequately set up to YOUR satisfaction.
4) look at other boats in the same price and size range to see what you might be overlooking.
5) TRY to get inside info on the specific boat. I would expect in most cases the boat would have to be a notorious racer or prominent accident victim to have any widespread opinions about it floating around.
6) recognize that a boat over 10 years old WILL have issues, so perfection will be near impossible to come by. Also, your electronics will be ready for replacement on a 1992, unless the previous owner has done it recently. If the boat looks REALLY clean, and there are maintenance records backing up good practices (oil changes, etc.), those are good signs.
After all your analysis is as complete as you can make it, and you decide to make an offer, use a surveyor of YOUR choosing. I have had the same surveyor for the last 3 purchases I have made, and he is worth EVERY PENNY. Sam kept me from purchasing a real dog, which led me to a much better boat of the same type (which he ALSO surveyed for me).
All this being said, I have owned (3) Catalinas ( a 22, a 350, and now a 310). They are well made coastal cruisers with lots of features and good quality rigging and accessories. They are a LOT of boat for the money, and hold their value quite well in my experience. They sail good to very good, but most are not consistent race winners against some of the real performance boats out there. However, those performance boats often suck as cruisers, so...
Catalinas have sold thousands for a reason, and I think it is because of their quality and their value. I have certainly been a satisfied owner, and do not hesitate to recommend them as a great above average cruiser with good sailing capabilities. I could easily start a firestorm here by comparing them (favorably) to other brands, but I won't.
My wife and I feel safe aboard every Catalina we have owned or sailed upon, and the boats have always taken good care of us (up to 30 knots wind and 6 foot seas so far, here in Puget Sound). If you buy right, and take care of your Catalina, I think you will be satisfied also.
Good luck!
Jon Freeman
C-310 "Summer Sojourn"
Seattle/Tacoma