A friend of mine asked me if a deceased's shoes should be disposed of, and if so - why.
Here's where I am so far:
I found that Nitei Gavriel in (Availus vol 1 Chapter 132 pp 714-715) discusses this matter, and basically the ruling is that should not wear the shoes of a mais, but rather dispose of them - because of Sakana (Danger)
As to why specifically wearing the shoes of a mais (as opposed to garments etc) is a danger - the Nitei Gavriel bring 2 reasons:
1) Shoes contain sweat from the feet of the mais (Keter Shem Tov)
2) This could bring about the wearer of the shoes to dream about the mais taking them back... which is a bad sign (as per the dream sugiah in the Gemara Brachot 57b) - (Koret HaBrit)
This probably answers my question, but I'm still not sure I fully understand the above reasons..
also: is the above mentioned danger a spiritual one or a physical one?
There are many Jewish customs that stem from the desire to avoid anything associated with death. See here.
This link answers the question more specifically.
This particular custom comes from the Sefer Chasidim, and there are various interpretations as to the rationale.
The Talmud says that a dream in which a dead person comes to take back an object is a good omen unless the object is shoes. Therefore we don't take their shoes in order to avoid causing a bad omen in a dream. According to this reason, the prohibition applies to all shoes but not to socks. Used shoes would presumably be okay because we don't know that the previous owner is dead and therefore won't cause the bad omen.
The leather of the shoes may absorb contagious disease from the deceased and spread it to the wearer. It seems to me that this reason would apply to socks as well, but could be rectified if they were sanitized.
The custom refers to shoes made of a deceased animal that died from a contagious disease and the problem is contracting it from the contaminated leather. According to this view, there is no problem wearing the shoes of a deceased person.
In a recent Friday radio Q&A program, R Avraham Yosef (previously Chief Rabbi of Holon, son of R Ovadia Yosef) said explicitly there was no prohibition of wearing a deceased person shoes, except for those he was wearing at the time he passed away. I now found the reference to Yalkut Yosef 21:11 here.
Personal opinion: throwing the shoes away rather than donating them might actually be a transgression of the aveira of baal tashchit.