The one I learned to play on an old borrowed Aspen I now loathe due to the narrow neck and difficulty tuning it on the bottom two strings. I bought an Epiphone PR 350 and that's when I improved considerably. After I got decent with it my wife bought me a Takamine F 400 aka a lawsuit Martin 12 string. I know a real good shop in East Tennessee where I got it used for a bargain. Someone had strung it wrong and the store had just took it in on trade and hadn't fixed it yet. The store is also a Martin dealer but no way for me to ever get that kinda cash. LOL. But well known pros do buy their Martins there. It's north of Knoxville and been there for decades.
I can pick one of my guitars up sometimes and play and it sounds out of whack kinda flat. I check the tuning which is usually fine and put it down. I can come back in about an hour and it sounds fine. Nothing was changed on the guitar itself. I know it's my own hearing doing it. I do believe that it is mostly technique more than anything that can actually change the sound. But there's just too many possible variable factors that make it difficult to play the exact same way each time and get the exact same sound. I would say it would matter whether a person uses a pick or not also. Change picks it changes tone level. I would assume any way. I don't ever use a pick except when tuning.
I agree with everything you say here. Many people are discouraged because they start off on bad guitars...that are hard to play and hard to tune...then that one comes along and you take off.
I think I’m done with any major guitar purchase, but I love having them around me.
My D-18 Authentic came in yesterday. It’s a Mahogany body. I love it right out of the gate.