What are the rasons for a smelly penis?

Poor hygiene. The main reason for a smelly penis is usually poor hygiene. The other common reason is scarring of the foreskin with difficulty in retracting the foreskin which causes an accumulation of smagma underneath the foreskin. If this area is inaccessable to be cleaned adequately, it will cause an odor and some white discharge. An uncommon cause for a smelly penis is penile caner.