None of Carmen's forms are associated exclusively with positive or negative emotions, but some lean more towards one side than the other, the biggest tell for this is the emotion Carmen's chosen to name the form after.
Cozy.... The largest; the softest of them all... And the rarest. You gotta be entirely trusted by Carmen entirely, and willing to be overly cuddly and coddling to it also. The most emotionally truthful Carmen....
There are a few variants of Carmen, magic and all that. They're based on emotional state! (The emotions they're named after aren't the only emotions that are associated with them however)