I don't usually wash under my foreskin as it makes me uncomfortable to pull it back.
That's probably the reason for the smell. And you're right about it being a turn-off for sexual partners, particularly for oral sex. It's essential to pull back your foreskin and wash the penis head thoroughly every time you shower.
When you say it makes you "uncomfortable" to retract your foreskin, do you mean your exposed penis head is painful to touch? If so, you need to make it less sensitive by touching it as much as possible: you can do this by retracting your foreskin in the shower, soaping up your penis and touching it for a while each day. At other times, use lubrication on the exposed penis head to make it easier to touch.
If retraction is "uncomfortable" because your foreskin is tight, find the sticky headed Stretching To Fix Tight Foreskin (Phimosis)
at the top of the Men's Health Message Board and do those stretching exercises (with an erection) regularly each day for a month.
You should also retract your foreskin when you pee: it's cleaner that way.