If i discard down to three, keep a curse, play Masq and draw another Curse, shit.
Pass one Curse, trash the other. 
By "trash the other" you mean the Curse passed to the Masquerade player, i guess?
I'm talking about Masquerade/Discard attacks too much here, anyhow. My actual point about Masquerade was this: Often the card is associated with Masquerade/Discard, or even the infamous KC/KC/Goons/Masq pin. And nobody denies that those pins, even incomplete ones, are strong. But usually a component of that pin is lacking. Usually Masquerade will just be Masquerade, which means "+2Cards, remove one or two cards from your deck, gain a Silver if you are lucky". It's strong, sure. But Rebuild is stronger. It needs nothing to rely on (except starting Estates help it), it isn't harmed by most attacks, opponents can't guard against it, and - what may be worst - it doesn't even take a lot of skill to use it. Both are not ignorable on most boards. But on a Rebuild/Masquerade board, i'd ignore Masquerade for Rebuild.
