I have a soap dish attached to the tile in my shower. It's caulked around the outside, so I can't tell how it's attached. My neighbor believes it's just attached with mud.
Any suggestions?

There aren't too many other ways to attach soap dishes except with mud material on the backside of the soap dish. What are you going to do with the blank space? Attach a different soap dish?

Wrap the dish with a rag then tap tap with a hammer. Then small putty knife or chisel. You'll discover the dish is not covering a tile, but takes the place of one with the flange overlapping the adjacent tiles.

Is it a standard 4x6" dish or something else?

Jaz