Note: I may not get all of the Problems with this but.
In My EMS Classes we are taught about BSI Body Substance Isolation. Which I can see in this thing she did wrong one, she should of not taste test people's food with her finger, secondly she should have washed her hands between tasks occationaly to prevent pathogin spread. I'd also like to point that she touched that spore on her neck which would also create pathagins to spread onto her hand and removing the case for the Dessert Tray even though I'm not someone in the food Industry that would also create a hazard if someone coughed/sneezed on it.
Simple and short: She should of followed proper hygene and wash her hands and if she touched anything like a possible medical hazard like on her neck she should of immidally washed her hands.
Im pritty sure there is more to this than just what I said but its a main part.