I've had targets show up with wrong information, many of them war ships. I've seen an AIS target that had an info length of 160 feet but when I got a visual it was a small private vessel somewhere around 40 feet. Could have been to mask the fact that their were probably only 2 persons aboard.

War ships,, either no info or completely bogus info. Many times a war ship wasn't even transmitting as I would have a visual but no AIS signal. I've never seen a war ship with more than basic AIS info.