How often do you have to clean a guinea pig?

on average they are cleaned about once a week.

Your cage should NEVER smell. On average, cages are completely cleaned once a week (bedding replaced, cage sides and bottom wiped clean). You will need to spot clean particularly wet spots an additional 1 to 2 times during the week. Some people spot clean every day.

if you have 1 about once a week,

if more, change accordingly.