A friend of mine had a night mare with the BATF on his last, his fourth, suppressor application. They dug up some charge that he had gotten back when he was 18 y/o, that had been expunged. BUT they used that excuse to deny his fourth application. They made him jump through all kinds of hoops for over a year, to prove that the charge had truly been expunged.
He did finally get the approval for his fourth application, but it was a real pain the buttootie.