Flip Flops, Flip Flops....Flip Flops.
I had the same debate when doing my Lucy cosplay and I agonized over it. I wouldn't trust the floor and usually when asked for a photo I'll take them off or just take the photo with them on.
For sanitary purposes it's never okay.
Utena from Revolutionary Girl Utena [Complete]
Hannah Anafeloz from Black Butler [Complete]
Rei from Neon Genesis Evangelion [Complete]
Vanessa from The Little Mermaid [Complete]
C2E2 [Saturday Only]
Anime Central 2014 [Saturday Only]
Anime Midwest 2014