Question: I recently picked up an AU 1865 2 Cent piece with deep Die Clash marks on the reverse. Do the die clash marks add any real value? I don't have a picture scanned, but they're the tight horizontal lines on the obverse evident below the 2 on the reverse.

I personally love clashes, but they are a pretty normal occurrence in the minting process and usually neither add or detract from the value. Morgan dollars and Franklins are the exceptions to that rule. And some clash lovers may pay a little extra for a really nice clash. So I really helped out here with a definite ....maybe.

Kind of depends as already noted. First are you sure it isn't an after mint problem? How bad is the clash or whatever it is? At most coin shows I've noticed over many, many years the serious coin collectors do not want anything at all wrong with the coin. Then again there are many error collectors out there and more all the time so if it is really a Mint Error it would bring more as an error to an error collector. I would have to say it all depends on what you want to do with that coin. If it's for yourself, don't worry about it. If you want to sell it, then that's a different story.