As your partner in crime in this Bulgarian National consume adventure, and with all two of my years as a Seattle resident, I think a couple of things played into people giving us space. Seattle prides itself on two things: being (icily) polite, and being accepting of All Kinds of Weird Stuff. So catcalling, or even asking what we were doing, would break both of these norms. I also think you might have gotten more attention if you were alone, or if I had also been dressed up. OR if the secret part of what we were doing was bigger/ louder/ more attention pulling.  I don't think that Seattleites are desensitized to things, I just think the culture says to give everyone space to do their own thing. Even if your thing is dressing up in your Bulgarian National Costume on a Saturday morning.