When we're hiring decorators, we can't have them stage, but we test the heck out of them when they apply: Here's an 8" cake. Fill it, ice it, give it borders and roses, write "Happy Birthday" or "Congratulations". We time them on this. Anybody who takes more than 10-15 minutes is automatically disqualified. Anybody who doesn't know how to do any of those tasks is automatically disqualified, If you've got the chops but are obviously slow because you're nervous, which is understandable, we might hire you, depending on what else you can bring to the table. We'll take a second look at an eager, heart-on-fire newbie because we know they tend to learn fast as in "When I'm not here I'll practice on my own dime with my own tips and icing and dummy cakes at home". We currently have a relatively new decorator who does just that, and her skills have grown by leaps and bounds!
We once had a woman come in for an interview bearing a very professional-looking portfolio. She passed the interview with flying colors. When it came time for her to do the "test cake" as I explained above, she was at an utter loss.. Turned out she had printed off different cakes she'd found online and put them together into a portfolio so she could get an interview. She had no idea she'd be tested. She only had one maybe 2 cakes in her entire life, back when her daughter was young. We felt badly for her because it was so obvious she needed a job, but there was no way we could have her learn from scratch on our dime, never mind duping us with the "portfolio".