To actively look for strange phenomena and so forth would probably be Wits + Occult, but unless you have a clear idea what you're looking for, the roll is going to take a penalty. At the moment, the penalty is -2.
Sebastian also needs to roll Wits + Investigation + Auspex, with a target number 4+.
The woman with the two leads nods to Madison. The two near-nude individuals she is leading lower their eyes, avoiding making direct eye contact.
As Madison and Sebastian approach the bar, they see the bartender is dressed in a tuxedo and a red rubber, full-head devil mask, complete with horns and a pointy beard. There are a few people hanging near the bar, including a stunning woman dressed to show off truly impressive cleavage, and a guy who seems entranced by the sight.