Smelly helmet.

I find its gloves and helmet which get a bit fragrant. I wash the gloves and I wipe the helmet pads with anti-bac wipes. The helmet's a Bern with an inserted visor and sweat band, and that gets washed,

(That said, I recently started wearing a cap instead of a helmet).

The pads in the Mojito come out.  I put them in a net bag and in the washing machine with my kit once every couple of months.  And like racingcondor have 2 sets.

Smelly helmet? Shower and change your shorts.

Definitely clean the pads regularly. Salts can build up as swest evaporates from the pad to be released all at once if you get caught in heavy rain. It's like having saline squirmed in your eyes.

Unless of course you wear a hat/cap under your lid.

I used to rotate 2 sets of pads (works well), these days I tend to just rinse the helmet in the shower occasionally.

Helmet pads are held in place with velco. Peel the pads off and hand wash with mild soap, like Dawn. As far as "put the helmet on a gentle washing machine spin" that's a very good way of beating the crap out of it. Hand wash the shell too.