People often ask how they view FTT; is it humiliation or worship or as a reward, or what.

I believe that it is D) All of the above, and more. Here is the 'more':

I always viewed it as a ceremony, a ritual that confirms and acknowledges the places that the Mistress and the slave hold. The first Mistress who ever took a shit on me said "To me, this is like getting married". What she meant is that it is a ceremony. Even more so than a wedding, there is no going back. Once someone takes a shit in your mouth, your roles are defined and set, forever.

I enjoy the scenes where the Mistress does it because (a) She can and (b) It cements her relationship with her slave and (c) because she gets a sense of elevation out of it.

For the slave there is a feeling of acceptance. The Mistress is making it clear that she is way above him on the evolutionary scale, but there is still a role for him in her life.