One time I went into a restroom and a girl followed me in. I signed an autograph for her in the sink. It was pretty funny because she was in a guy's restroom and she wasn't embarrassed at all. ↗
I got very cross with the term, kitchen sink. It just meant that you invaded different kinds of houses, where it was very difficult to avoid kitchen sink. ↗
When you're writing about people that are not very well off, you seem to see the kitchen sink. So it was a bit of a sort of cosy phrase that got used a bit too much. ↗