[Wally]

I read line of necks and neck set angles on every guitar I pick up. I look across the top of every guitar I pick up. I do these things before I play the guitar.
I use a mirror to look inside every guitar that has any issue with the top. When there is an issue with a concave top and/or a 'rolling' bridge, I expect to see loose or broken braces. When there are no loose or broken braces, there is a possibility that the guitar has dried out, the top has 'shrunken' and therefore the top no longer does what it was designed to do....hold the bridge in place (maintaining proper scale measurement) and pump air. It still pumps air, but the air carries intonation-problem-plagued notes adn action issues interfere with playing. Most guitars that I have seen with this type of problem with the tops will come back with humidification. I use humidification of dry guitars with 'shrinking top' problems before working on them. IF long and gradual humiditification of the woods doesn't bring the top back into shape, there are other issues.
Then I start looking again at the bracing. Popsicle braces don't impress me. I have seen them in two lines of guitars....one USA and one made in ASia..just one guitar actually from Asia. I have seen a number of guitars from the company in the U.S. that have this construction technique. I have seen numerous examples of this type of guitar lose the integrity of the top and develop serious playability issues. I do live in a dry area, and the winters are hard on guitars. Most dryness issues can be dealt with. These gutars have not responded like other guitars with more traditional bracing methodss used in their construction.
A mirror is a valuable tool when looking at guitars. KNowledge of line of neck and neck set angle is basic and important, imo. Looking very critically at every guitar I pick up has broadened my understanding of what the machines are supposed to be, what happens to them and what to do about those problems. I am still learning after all of these years, and I have learned that I personally would not recommend any guitar with popsicle braces to any of my friends or customers. I do not buy those guitars for personal use or resale purposes.
YMMV