One time i was vsing a guy at the local shoppe. He had an Imperial Guard company on the field, I was using my space marines (yay!) As we were deploying he said he was keeping one unit in reserve. I didn't question him on it becuase I wasn't really concered until I noticed he only had what I later learned was about 250 points of Guardsmen and chimeras on the field. Now this being a 1000 point game, I was confuzzled to say the least. So we get the game rolling and each turn he rolls reserves, he doesn't succceed until turn 5. By this time all I had left was my Terminator Librarian and a Predator Anhilator, when suddenly he shouts "BONUS!" and sets his forgeworld BANEBLADE on the table. This thing was pro painted (i excpect he hired someone to do it.) and looked gorgeous, was even prayed down with a varnish or sealant of somekind to preserve it. Anyways, First round, my Librarian fires a Vortex of Doom at it, but fail the psyker test, but pass the armour save. I hold my Predator Back a bit and fire its full volley of lascannons at it, but they plink off (best was a 3). He decides to taunt me and fires ALL of his weapons at my librarian. So, i make about half the armour saves and failed the rest. The rest of his guardsmen just kinda sat around smoking sinsticks apparently having decided to let the Baneblade finish me off. Next round comes, I fire my lascannons at his Baneblade again and rolled THREE 6's, scoring penetrating hits. Next roll for effect and got two vehicles destroyed and one vehicle exploded, and toasted all three Structure points on the Baneblade. He just kind sat there open mouthed because that one shot basically won the game, since he was banking on just killing me off and not taking the tokens on my half of the table, so my tank was in scoring position for three of them (being the closest unit) while his Guard only had 2.
Never saw the guy again. Just goes to show you. An unpainted and *very* poorly assembld (there are gaps in the armour, and the sponsons and turret are glued in place) can still beat up a supertank if it gets lucky.