They are BAD. A coffee cup of water up to the handle bristles-down, a bit before. A heaping tablespoon of Oxyclean tossed in and then the brush, bristles down.
Let it fizz until it stops fizzing. Check the water as you pour it down the sink......Likely nasty! Lots of rinsing.
Give it the nose test. Have had to do some twice, but never 3 times.