Rotten windows, rotten walls, rotten decks, any sign of stain or discolouration on the inside teak, look under the side decks in the staterooms for stains, mildew smells, rusty fuel tanks. Get the decks wet and look for bad seams.
100% of the CHBs I looked at that were for sale had some or all of these defects. Not saying there aren't any good ones out there, just that there are many bad ones and that's all that I saw.
Don't believe everything that you think.