I'm still trying to work out what the question means! So I tried to break it down in my head. Price, bling, sound, general quality etc. Any guitar with an over inflated price, talking over $15000 or over here £12,000, just has to be over rated. You don't pay that sort of price for sound and playability. Bling, any guitar with more than decent wood, good tuners, reasonable binding etc must be over rated. MOP on every edge and nook and cranny does not improve what a guitars does. Sound, any guitar that sounds good to the player is not over rated, unless it falls into the super price or super bling category. Under rated guitars are generally those that are cheap but have good tone and playability. It all boils down to value for money really, but then that depends on how much money you have, or in some cases, want to invest. Personally, I think Epiphones make some good acoustics, Recording Kings always feel stiff to me, I like my J15 and generally think Martins and Gibsons fall into the middle ground, not over or under rated. One of my favourite guitars is a Harley Benton all sold dread cedar/hog which just sings, £220. I have never seen a Taylor that I lusted after, but I think they are over rated because so many seen to be priced far too high for laminate B&S. Just me trying to work it all out in my head! I could be totally wrong, mixed up or just plain ignorant