I'm bisexual and I've been into me wearing sandals in bondage for years. I equated to how women like wearing heels in bed. I definitely don't think it's "normal" in the sense of being common but ...

I have this sandal fetish to, also slip ons without socks (like Tom's) are a distant second for me, they feel like "man flats". I am not sure why this is but it's nice to know I'm no the only one.