Originally Posted by invisible

I do understand that subject of this topic has potential to turn into flame, but still wanted to share my personal experience. Which can be summarized with a statement - 'politeness does not usually help'.

Cases:

- people (usually teenagers) playing music thru earphones loudly enough to wake me up while asleep on a plane
- people invading in my personal space - taking armrest/footrest or putting their belongings in my space
- people come in on packed public transport (bus/train) with backpack on and do not remove it.

What I found that if I politely ask to stop doing it, they will do it for a while and after some time forget and do it again.

So instead I adopted the practice to tap on shoulder noticeably using my index finger and looking directly on eyes tell "your earphones are too loud; take your feet/arm off; take your backpack off". And if they stare, I say "NOW!"

Works 100% of time and I do not need to repeat myself again once more.