It is a superstition. You write the name of a person you like on the bottom of your shoe. If the name fades away fast, the person does not have the same feelings. If it stays for a long time, that person likes you. In this case, the sentence you quote means that the person mentioned does not have the courage to really find out if the person he/she likes feels the same way, so the image is that he/she can only use some superstition to find out.

thank you kevin. I read this from a book written by an America author. So, I think fdmaxey, who is from that country might gave the correct answer. anyway, thanks a lot

This question has already been answered before. We need context to answer it properly. As it stands it means that the relationship isn't worth anything.

Never heard this phrase in the U.S. before. To be honest, if I were to hear someone say it I might think that they were cursing the person whose name was written on the bottom of the shoe. However, after thinking about it I can understand how this would be a valid metaphor.