because of the oils from the hair. This is when cleaning the skin with
alcohol is useful.

I find putting the patches on the ends of the nerves where you "feel" the pain, is less productive and can make the pain more intense even.

I put them higher up along the nerve path, and stop the signal that way.
I have no increased pain from that style.
I would NEVER use them on the bottoms of the feet myself. They are much
more effect on the top toward the inner ankle bone (just below) since that
is where the nerves exit the tarsal tunnel.

When I first got them for my MP... years ago when they first came out...I tried putting them where I felt the pain in my thigh. I learned very quickly that was a waste. Now I use them based on anatomy pictures I look up, at the exit of the nerve from the abdomen thru the inguinal opening. They effectively stopped my pain in 14 days, and it has not returned! (I do have some left over numbness, but I can certainly live with THAT).

For knee pain I only use them behind the knee. They work far better near the meniscal nerve, than on the front, where I feel the pain.

So over the years I strongly recommend careful placement for best results.