The key is to be completely honest about the condition in your listing and price it according to what similar, played-condition cards have recently sold for
You even get Biogenic Ooze for counters
If the chosen permanent is a token, Malleable Impostor copies the original characteristics of that token as stated by the effect that put the token onto the battlefield, with the listed exceptions
The two most famous being Lightning Greaves and Swiftfoot Boots which will grant the creature they are attached to Shroud and Hexproof, respectively
Blue decks might already be tempted to play something like Vedalken Orrery or Leyline of Anticipation
Here is the list that I would play tomorrow if I went to a tournament: Creatures (24) 4 Arcbound Ravager 4 Ornithopter 3 Steel Overseer 2 Memnite 3 Etched Champion 4 Signal Pest 4 Vault Skirge Lands (16) Spells (20) Against a lot of decks my Thoughtseizes were awesome, and in most of my matchups I wanted to board in Spell Pierce