I don't mind showing ID and walking through a metal detector. If it goes off, wand me, fine.

I think it's unreasonable to make me take off shoes and walk across a dirty floor.

I think it's unreasonable to make me take off flip-flops so that you can wand my bare feet.

To me, reasonable is the intrusiveness v. effectiveness. I don't think the mangnometer is overly intrusive. I'd rather there be no guns in the cabins (air marshals included), so I don't really have a big problem with that.

But considering all the other things that could happen during a flight, most of which have been discussed here ad naseum (nerve gas, non-metal sharp things, unscreened cargo, unaccounted-for surface-to-air missles, etc.), I can't justify a great deal of intrusion, as if someone really wants to bring down an aircraft, I think it's quite possible for them to do so.