Ahhhrgh... now you guys tell me teak decks are bad!
Just kidding. I was in the same boat. I swore to myself to never buy a boat with teak decks and acres of varnish. Read all the horror stories. And then I bought a 20 year old GB52.
Decks look fine, no leaks but I'm sure there will be some maintenance required the next 10 years. Telling my wife she needs to learn how to varnish. I don't have the patience for it.
After 39 yrs, my teak decks are still OK. Yes, there are a couple of boards that have worn away more than they should, but only a couple. The rest are going to be fine for quite a while. I have screwed and plugged fastening, and so far, no failures. When I bought the boat, 26 yrs ago, the broker hosed the decks and as they dried, noted that there were no signs of leaking, as everything dried properly. Any wet spots would be an indication that water was remaining where it shouldn't.
I learned right away to avoid chemical cleaners, as they erode the softer wood quickly and there is no fix once that has happened. Clean occasionally with a soft brush and mild detergent. Varnish around the perimeter of the deck and, if you have a "king" board up the middle of the foredeck, varnish is permissible there. Otherwise, let the decks go gray and they will give you good service.
A friend with GB teak decks doesn't have a wider perimeter board or a King board, so if yours look like his, no varnish at all.
On mine, the varnish prevents any wear on the perimeter and king, so gives me a good reference to see if, or how much the rest of the decks are wearing. So far, no measurable difference, but for the boards I noted at the beginning.
If I was in the market, a good survey would tell me what I would want to know about the decks. I wouldn't rely on Chicken Little on the internet.