Was thinking about writing this for a while, but an experience I had gave me the motivation to finally do it.
While on a business trip to Singapore, I went to Black Tap at the Marina Bay Sands for Lunch. Sitting on the Sofa, the (Korean) guy in the table besides me kept bouncing his leg. Had two options: to tell him to stop, or to move to a chair. I moved to a chair and started planning what to write this blog post.
In Japan, it is considered a bad habit, one that shows “bad education”. The wiki page for 貧乏ゆすり is not linked to a page in other languages and mentions
多くの場合において品を欠く行為・悪い癖だとされる
Which means vulgarity and bad habit. The literal translation of 貧乏ゆすり is “poverty fidgeting”.
Did not research, but not familiar with such contempt to fidgeting in other cultures. If we look at the English wiki page for fidgeting it tries to explain the condition and reasons for it, not judging it
Fidgeting is considered a nervous habit, though it does have some underlying benefits. People who fidget regularly tend to weigh less than people who do not fidget because they burn more calories than those who remain still, which is called Non-Exercise Activity Thermogenesis (NEAT).[13] It has been reported that fidgeting burns about 350 extra calories per day.[14]
Living in Japan, I got used to thinking the same way. I notice when people bounce their legs and show nervousness. Was surprised when at a meeting a Japanese customer was bouncing his leg and even discussed it with our partner.