my boat stinks
As an FYI: all head hoses eventually will have the smells permeate the hose. However, some take much longer than others. PS did a study of head hoses and found that Sealand hoses do the best job of keep the smells contained inside the hose. They are white, smooth hoses--not the corregated like bilge pump hose. The black rubber absorb the smells from inside pretty quickly.
When I replaced mine, I used the Sealand and it has lasted OK for probably 3 years now. Available from West Marine.