We fly when we have to, and it is really smart to be cooperative and have a good attitude.
I have not had any problems including luggage searches or pat downs with my metal knees.
There are a lot of people out there, some of whom look like us, who would love to bring a dozen planes down like 9/11. Times have changed, and if I did have a problem with a screener, would be businesslike, ask for a supervisor and tell them the problem in a courteous way.
A BIG BTW is never refuse their request to screen you, or your day will be ruined.
Why?