The appearance of age argument is flawed, just like the rest of the young-earth argument.  Had Adam been aged artificially in the same sense that the universe and earth bear the undeniable stamp of antiquity, a physical exam would have revealed worn dentition, liver spots, scar tissue, calluses, blood cholesterol, wrinkles, and all the other physical signs of an aging adult.

The notion that the universe was brought about with an apparent age, or that it looks old but is really young, crumbles under its own weight.  How ironic it would have been for God to have commanded us, Thou shalt not bear false witness, and have expected us to adhere to a criterion that He would have violated from the very beginning.

From Romans we find we are held accountable by the evidence of nature.  For the invisible things of Him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse (Rom. 1:1:20).  Had an artificially-dated planet been palmed off on us by a clever sleight-of-hand artist we would not be without excuse, we'd have a great excuse!

Inherent with the appearance of age argument is a classic Catch-22.  If the world is old in complete agreement with the way it looks, then why would God give us a book telling us it is young?  And if the world is young, then it had to be manufactured deliberately and cleverly to look old.

Thus, the orthodoxy of young-earth creationism poses an insane dilemma; if the world is old, God would be a fibber, and if young, He would be a counterfeiter!  Taking young-earth dogma to its conclusion, if we could not trust God to give us a true history of the world we live in, how could we trust Him to give us true history and true prophecy in His Book?  A god who could falsify nature might falsify a resurrection!

Ironically, these implied allegations raised by those who profess to be believers call God's very credibility into question.  True words demand true works.  For the word of the Lord is right and all his works are done in truth (Psa. 33:4).

I can think of only one reason that the earth would look old, and that would be so that when we observe it, we think it is old.  If God wants us to think that, then that is what we should think.  I would rather believe it looks old because it is old.  But either way, we should continue to think that way, since that is what He expects.  And if I found any evidence for a young earth, He could trust me not to blab about it.  If God had created the earth recently, but wanted to make it look old, the last thing I would do is bring up contrary evidence to point out oversights.

The perplexing theme of young-earth creationism is not that God made the earth with the appearance of age.  Rather, the inferred message is that God made a clever attempt to create an old-appearing earth, but thanks to the efforts of those hard-working researchers, they have uncovered His inconsistencies.  So, first they accuse Him of deception, and then they assert He wasn't good at it!  What a confused message that is.