That 'innocuous' comment has enough social subtext for people of certain viewpoints to find it repulsive. Like, say, a guy running an anti-bribery campaign.
Personally, I don't begrudge people paying more to get better service/food, but extravagant tipping for better service in a situation where people are expecting to be served fairly sends a strong signal: "I am too good for your rules."
Not everyone has the same outlook on life as you do.