I never tried that Bloody Mary shit, but i have been in a haunted bathroom before, lol. St. Catherine's men's gym bathroom in Vallejo, on a dare with like 4 others. We went in with the dim light on, saw a shadow running around in the corner, the light turned OFF then flickered, a toilet flushed, then we ran out there like some pansies, LOL.
In all seriousness though, that shit was scary as fuck.