Some general guidelines for evaluating them, with needed context to improve their value.
Double-faced cards. Depends on the transform condition, but are usually good when easy to transform, or you drafted a werewolf deck. In constructed, werewolves seem bad because they are usually not efficient until transformed, but some cards have decent conditions to transform.
Delirium. It’s easy in limited to get to three card types in the graveyard – creature, sorcery and instant. The fourth seems really hard, specially when the basic land fetcher costs two to activate. If there’s land sacrifice or good discard outlets, the mechanic gets good. It seems fit for constructed.
Madness. It’s generally mad, but also requires discard outlets. Maybe there’s a deck with discard, delirium and madness.
Skulk. It’s bad evasion unless there are pump effects at instant speed, that can be played after blocks are declared.