My memory is leaky as it is... The milk thing was from a few years ago. I do know we used milk a lot when I worked with antibodies, it generally binds to everything so it decreases the background noise. I was skeptical, but after thinking about it for a while, my thought at the time was that milk would bind to viral coat proteins and block the virus from interacting with cells.
I did just find this paper (it is somebody's thesis, not peer reviewed as far as I can tell).
https://kb.osu.edu/dspace/bitstream/...NDA_THESIS.pdf. I'm really supposed to be doing my taxes or I would research it further.