No good in my opinion. If you're going to buy Messi, spend the extra bucks and go to Icons. He is a sponsored signer for them and you'll have piece of mind.
Martin, I recommended Icons to you - this is your best bet for peace of mind as Mike rightly said. If they have a signed football there, just buy it there. The prices for their autos are actually reasonable, imo, for some items. I wouldn't purchase some items, only because of the ink used and I'm fussy, haha, but if you want a Messi autograph, just go through Icons as Mike says. You can't go wrong.