I don't think I have had the interest to check anyone in many months out of the blue. Sometimes I will ask to check someone in a party whose performance seems abysmal to see if outdated equipment is their problem.
Then I might reply with something alongs of the line of
"Come on man you're in Yhoater Jungle, time to replace the old Onion sword."
When people check me, it's just more of an annoyance than something that offends me. When someone takes 2 seconds to ask me if I mind, I give them a little more respect.
It's like... if you have a really nice car, you'd want to show what's under the hood. But then, you wouldn't some stranger to just pop the hood and take a peek without asking you? That's how I view checking. Because they are altered to the fact you are checking them, it's more than just looking at them, you should get permission.