40% think farts and seeing someone get hurt are the pinnacle of humor, with the true comedic genius defined as someone who can fart AND belch simultaneously while accidentally setting themselves on fire. This doesn't really rise to the level of "good sense of humor" IMO. They don't like to think they enjoy seeing other people suffer, so they won't say they laugh at someone who just fell down a flight of stairs. Instead, they tell you they are laughing at someone who got "pwned". Don't agree? Here, smell my finger.
25% have a genuinely good sense of humor which I define as appreciating a quick wit, the ability to laugh at themselves, and an ability to see humor in many situations and not just while watching a stand-up comic perform.
20% have a good sense of humor but ruined it by become snobby about it, so they won't laugh at anything not sophisticated or upscale "enough". They sneer at the genius of the Three Stooges because it's slapstick, so therefore it could only be funny to double-digit IQ owners and people who (shudder) actually work with their hands.
10% think everything is funny and don't have the innate calibration to distinguish between something that was meant to be funny and something that wasn't.
5% don't think anything is funny.