I once worked in a company that allowed smoking before and after office hourse and during lunchtime.
They had just experienced a break-in, where all the RAM was stolen from the computers (Macs BTW, 6100 and 7100s), so they had bought steel enclosures for all them. So didn't help with the circulation.
Some keyboards were so filthy, you could not see the keys - I think everyone assumed that the keys had just worn out and said nothing, until I organised a cleaning company to clean the computers - the cleaning company ran out of cleaning fluid by 10:30am and had to come in for another 2 full days to get rid of the gunge that had accumulated on the computers. The Macs at that time were a kind of beige (if I recall correctly - 1996), but the ones in our office were a deep shade of grey.
"Wow, my keyboard actually has letters on it" was a common exclamation that week.