My tip ~~~ I always have dishwashing liquid in the office.
Here's my bottle of Joy diswashing liquid at the moment (placed in my old Bath & Body Works lotion container).
From experience, the life span of my containers tends to be longer now since I began doing this small thing. God knows how many plastic containers I've bought already. With my many BYOB days, most of them look worn out, unpleasant and old already.
After eating, I immediately drizzle some Joy to my plastic containers to avoid them from becoming yellowish and old. Any liquid hand soap simply don't work for me.
I usually find time to go to the pantry to wash my own plasticwares so that they remain clean and smelling good. However, when I'm just too busy, the dishwashing liquid will give our helper an easier time washing them, plus the 'sebo' is instantly removed.
Do your househelp a favor by cleaning up your BYOB containers. It's nothing much, but it's definitely worthwhile doing. :-)