As majority of CX fares are bookable through their website or travel agents, they are in fact already offering 'sales' as their published rates from anywhere other than US/Canada are so much more higher.

BA's fares are all published fares hence the use the term 'sales' to entice sales.

But CX is known to be much lower than others when its not ex-HKG. So yes, CX has sales ... almost all the time. They just call them 'promo fares'.