I don't generally jump into threads like this - I have used all sorts of gear over the years, and have been able to make most anything work for me. However, I got a Gibson Thor as part of a trade, about ten years ago, and it was - and still is - the worst amp I have ever played through. It is still sitting in the corner of my studio, as it has no resale value, and even if it did, I would feel bad inflicting it on another player. I thought that it might have had some technical issues, but when I brought it to my tech, he was surprised at what good shape it was in. He mentioned that those amps just sounded that way.
I did read of people modding them, to cut down the noise and get a cleaner sound, but I kind-of enjoy owning one of the worst amps in history, at this point.
I agree with your assessment. When I was checking out the one and only Thunderbird I've owned, the shop owner thought it would be cool to plug it into an amp of similar vintage. Crapola! My worst amp was my first. I believe it was a "Kingston". Maybe five watts @ 50% THD. Open back cab with a couple of el-cheapo 10" no-name speakers. It barely qualified as an amp.