Scorpio prefers dark looks;darker/tanned skin, darker hair and a somewhat more complex and/or psychology "clued up" personality. Even the "rebel" may appeal.Scorpio is energy that is fascinated with the "edgier" side of life. So people who are prudes, conservative or too "narrow"/ puritanical,seldom appeal.
Scorpio is mostly looking to unearth, to tear apart/rebuild in a better form and (at a higher level),to heal. So they may like "projects" or be drawn to people with "issues".
Scorpio(contrary to popular belief) is actually a "giver". Not so much a taker.
With Cancer, I often notice that the person that they are attracted to,normally has features(sometimes even physically) or attributes that they strongly associate with nurturing,mothering or caregiving.
So one tends to be drawn to people who are emotionally "in tune" and understanding. Or at least those who attempt to read between the lines i.e. emotional signals and body language(which are their key communication points)
Cancer is often strongly drawn to someone whom they perceive will "know" what they need-even before they have said the words.
Cancer may be the "nurturer".But mostly, Cancer is strongly self-concerned and is very much a "taker".
They may say they want you to be ok. But what they mean is, "I want you to be ok so that I can stop worrying". So its really not at all about you
Pisces often like the "spiritual" types i.e musicians, artists, writers etc. Or those who look like the type that worry about the ozone layer,religious devotees etc.
There is something "other worldly" about the person that Pisces is drawn to. Something about them that seems to transcend the mundane etc.
Either the person appears very impassive, even "chilled". Some may say "apathetic".