Re: Paris...
At least you could read what was on the keys!
I once worked for an outfit in the UK in the time before smoking in the workplace was effectively made illegal.
We had a combination of machines running DOS, Windows 3.1 and a Dec MicroVAX with serial terminals running the main finance stuff. One senior person in the accounts department was a chain smoker. The keyboards were the usual light brey/beige - except this persons. Dark brown!
They had started life as the usual colours - no prizes for guessing where the dark brown sticky stains came from. Anytime I had to look at a problem on that persons kit I wore nitrile gloves - which stuck! Should have had a full hazmat suit.