Generally I find the LAS TSA doing a tough job with respect competency & efficiency. but Jan. 31 changed that established perception. I generally tell TSA I have a metal implant & am sent through the body scanner which has a high rate of false positives generating a brief pat downThe agents always show me where the alerts are located on the outline character to show justification. (& mutual respect) & complete their task discreetly. However, on 1/31/18, I stood in the (TSA Pre Check) body scanner line which was unmanned by anyone for nearly 10 minutes. .Finally a very grumpy, scowling & arrogant TSA female agent appeared . the pax in front was motioned through quickly, but this agent announced not only was I going to get a full pat down, but a chemical shoe test, I felt like her Test subject. Unlike all the others ( I travel often) she offered no justification or concern for my unattended property end of the X-ray table- just shrugged. It is people like this woman who give TSA a bad name & clearly hasn't the aptitude for working with the public. TSA: hire our vets & send this gal to manners school..or better yet home.