Most acts of love are very simple acts of doing what needs to be done to take care of someone (or some dog). Feet are dirty and they need to be washed. People are hungry and they need to be fed. Loneliness sets in and someone needs a listening ear. Diapers are dirty and need to be changed. People fall into the power of sin and need to be saved. Not a lot of room for ego or false sentimentality.
To receive acts of love, however, requires that we accept that something needs to be done for us. Our feet need to be washed, our basic needs have to be met, we are not emotionally self-sufficient, and we have all messed up and need forgiveness and redemption. The problem with washing human feet is not that we find other people's feet smelly and disgusting, but that we are unwilling to admit that someone else might be able to do something that we need. "You will never wash my feet," we say along with Peter. Or, if we consider allowing someone to meet our needs, we would rather be pampered than loved. Demanding the full spa treatment keeps us in control and makes receiving love a luxury we are important enough to merit rather than a gift that we need.
My dog has none of those issues. She just wants to get her feet and belly wiped off as quickly as possible. She hasn't seen the rest of the family for twenty whole minutes and she wants to jump up on their beds and lick their faces. And if they are unshod and dirty, she will happily clean everyone's feet, as well.