Well, we're not so sure. The current US Mint facility at Philadelphia has been minting coins since 1969. However this year (2015) we have noted, as you may have, that the quality of the Philadelphia Mint Presidential Dollar coins has grown significantly worse. The Lyndon Johnson Presidential Dollar issue is even worse than the John F. Kennedy issue, which we did not think could be possible. General quality, eye appeal, blemishes, lack of brightness, errors, and many bag marks (surface scratches and dings) are very common. Some of these coins, quite honestly, look like they've been run over by a truck.
The Denver Mint seems to be doing significantly better at production quality, and has generally over the years. Here is another perspective from several years back. A contributor to Numismatic News, the most widely known trade publication, laments the quality of the Philadelphia Mint with regard to State Quarters, but it holds true it seems for most of their production:
http://www.numismaticnews.net/article/better_quali...
We have suggested that collectors contact the US Mint to make their opinions known. As these coins are no longer minted for general circulation, but rather for collectors only, one would think that they would pay more attention to quality. In any event, there really is nothing we can do about this, as the US Mint has complete and absolute control over the production of coins. Although sealed very well, only about 5-10 coins out of a 25 coin roll are in a condition which we would even accept as sellable. Cleaning the coins is not generally an option for dealers, and normally quality is high enough that we would not consider "cherry picking", and never have. However in this case, we must.
We have noted from several customers, however, that dipping individual discolored coins in a product call E Z est coin cleaner removes much of the discoloration. We do not sell this product ourselves, and generally recommend against the use of cleaners, however in this case, you may prefer the results, It is generally available at retailers such as Amazon.com:
http://www.amazon.com/EST-Coin-Cleaner-5oz-jar/dp/...
And should you wish to contact the US Mint:
http://catalog.usmint.gov/customer-service/contact...
Please be assured that we are only sending out the best examples that we ourselves receive. If you have any questions regarding this that we have not answered here, please feel free to inquire here. Thank you.