If you have to duck to keep from getting your head melted by APU exhaust, it might be an RJ... or conversly, if you stand in the APU exhaust in the winter to warm up (it's like a little piece of warm noisy smelly heaven)...

If you have to open 70 or 80 access panels to keep the TSA happy about your preflights (including the "Poopy Panel")...

If you've nearly been killed by hooking a luggage strap or loose piece of clothing on the stair railing on the way down....

If two people in the galley is one too many....

If you use more runway to land than the space shuttle....