After the tub or sink has drained, leaving suds, try this trick to get rid of the lingering suds.
Step 1: Condition It!
Take a bottle of hair conditioner, and squirt a little bit on top of the suds in the sink.
Step 2: Add Some Water
Run the water (you might need to close the drain for a moment and let water fill a little).
Step 3: Swish, Swish, Swish
Run your hand back and forth to mix the conditioner into the water as the water runs on top of it.
Step 4: Down the Drain...
The conditioner should break up the suds and send them down the drain with the water.
But only if necessary.