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The only time I've had something like that happen was a few years ago, when I was using a term in my ad that was trademarked by another company (after my ad had been running for some time) and they presumably contacted Google about it, because suddenly my ad got disapproved.
Normally, when an ad gets disapproved, Google AdWords sends you an email with exact reason "why", and they even give you a "suggestion" for fixing your ad.
That is my experience with text ads, for both search and content.
Oh, and there is a tool that lists all disapproved ads within the account.