I hate to say this, but after spending years in Asia dealing with customers and friends...I find it offensive when a guy shoves his dirty shoes at me. It was something that the older Asian guys taught me the first few weeks in Asia. So the Muslim’s aren’t the only ones who feel that way. A lot of places I visited..offices included, it was normal to take off your shoes at the door. So for years I only wore nice Bass Penny loafers one half size too big so I could slip them on and off without bending over.
Similar things happened to GIs fighting in the Pacific. It was called "going Asiatic." Wasn't a healthy thing btw.