Sealed drive will be smooth and 9 times out of 10 have flaking or white patches(blooming) on it.It will look varnished and might also be a grey dirty colour which will not wash off.If you re-seal do a test patch first to test for a re-action.Be ready for an abusive call 6 months down the line to go back and re-do because customers think it comes with a lifetime warranty,if i was you i`d stick to cleaning/sanding because you`ll only be sealing in July and August anyway and the outlay isn`t worth the profit.Dan