You might do a search as this topic was just discussed in the past few weeks. Here is the broad generalities of that discussion. Any boat this age is likely to have a whole range of issues, old sails, running and standing
rigging that is past its useful life span, engine in need of overhaul, out dated deck hardware, keel to hull joint problems, deck core problems, poor electronics, shot uplholstery and deck canvas, and so on. Any combination of these can quickly exceed the value of the boat.
The Coronados were cheaply built and were more subject to problems than a well built boat. Beyond that, the type of person who buys in inexpensive boat often takes short cuts with outfitting and maintenance as well.
So fair or not these boats have a reputation for having more problems than other boats of that era. That reputation affects resale as well as purchase, so while you can buy them cheaply, you are stuck selling them cheaply. Adding to this problem, they have aesthetics that are an aquired taste that most of us have not bothered to purchase. This further drives down their percieved and resale value. If you make the effort to fix one up, you are less likely to get your money out of the boat than if you were to fix up a better quality boat.
As to their sailing ability, they appear to have a quick corky motion in a seaway and would not be my first choice for an offshore boat. Because of mediocre ventilation and sailing ability they are not my first choice for a coastal boat either. If you are looking for a cheap liveaboard or you found one that someone carefully fixed up and is selling a bargain, they could make a reasonable live aboard.
On one of these BB''s there is a guy who spent some time cruising the Bahamas on a 35 and while his review is a little mixed he really found the boat good for that purpose.
Jeff