I can't speak to any specific examples, but iirc, many SS receiver/amp makers in the early 70s were engaged in a race to the lowest possible traditional distortion figures. The result was the emergence of transient intermodulation distortion (TIM). I'd avoid amps from that era unless you have specific knowledge of them (as perhaps you do). Amps from the 80s & 90s are a much safer bet.
What Gear Has Disappointed You?
While it's clearly not an absolute fact, we tend to have an expectation that a more expensive product should be better. Within a given brand it really should be a fact, but because there's a wide range of factors in play when it comes to pricing it's not necessarily true when comparing different brands. I think that it's fair to say that when we purchase a more expensive product we generally have an expectation that it'll perform better. In the cases where our experience confirms this belief it can be the result of the product actually being better and/or some expectation bias. In a sense, it doesn't really matter which it is.
With this in mind, have you ever purchased a product expecting it to be superior only find that it was clearly inferior in your experience?