We all hope there far and few in between, but as @gsxrpilot also confirms it, it's not as uncommon as you might imply.
The reason I bring it up in the first place is because an A&P mechanic friend of mine that actually works on GA aircraft and mooneys(my job is withe wide-bodies) advised me to go ahead with a pre-buy on an potential a/c I wanted to purchase.
The 69 M20C Mooney was coming out of an annual and (with your same original logic @A64Pilot) I thought why do a pre-buy if it just came out of an annual right..?
Well as many have advised here, an annual is just MINIMUM to keep it legally flying, and a PPI inspection is more for ACTUAL condition of the whole aircraft,airworthiness items and squawks.
So now I know better
Very grateful for your words here and will take this wisdom with me for a transparent purchase process of my first aircraft!
BTW,I did start a thread in the classifieds if anybody sees a 65-67 M20C, I would be grateful for the tip!