The problem is they get sweaty. This is a great time to rotate shoes. Let your shoes dry between runs. Sometimes this takes a few days to really get the foam dry. This will dry them with out heating them up, which can shrink or delaminate them.
Socks are also important.
Don't run in cotton socks. There are a lot of great sock out there that are made of coolmax, polyester. Also, don't wear thick socks during the summer. It looks like summer is here. This summer seems to be a hot one.