The heart break of checking.
During the build date of early 2000s to late 2000s all coaches built with fiberglass sidewalls are subject to checking. Dark colors are worse than light but have also seen it in light colors, just less intense.
You do need to get up close to see it. I've seen it in all high and low end brands, Newmar, Monaco, Country Coach, American Coach.
If your coach does not have checking you probably have not exposed it to enough heat and UV ray's.
I purchased my 2008 coach in 2013. It spent the first 5 years of it's life indoors. At 2013 purchase time it had no checking at all. We have been fulltiming in it for almost 4 years. After it's first winter in sunny Southern California the checking started. I have just excepted it.
That being said, why don't you consider this an opportunity instead of a problem. If the checked coaches are being discounted and the checking is just cosmetic consider that you can now afford a buy a higher quality coach that otherwise you may not have been able to buy.
If you plan on keeping the coach long enough it will depreciate so much, with or without the checking, that the financial cost is negligible.