After thinking about it for some time, it seems to me that the plain meaning of the Baal Shem Tov is this:
In reality, we all exist as guests of HaShem. As taught elsewhere, the idea of midah k'neged midah and the idea that one isn't punished until one passes judgement on oneself (as taught by the Baal Shem Tov) come together here: When we are hosts we have a chance to demonstrate how it is we would like HaShem to act with us.
We can either have mercy on our guests and shower them with every kindness, or we can take advantage of them ruthlessly. (has v'shalom)
It seems that the plight of the guest is a truly unique one. While you are unable to provide for and help yourself, even your own feeling of imposition or of unworthiness to be served is a function of how your host behaves. The unworthy in this world are fed the bread of shame in the world to come. This means that while HaShem provides for their every need, they enjoy nothing, for they are ashamed they can't take care of themselves.