I kinda have to straddle both sides on this one. On one hand i see your point of view in that this particular petsmart store hasn't adequately trained its employee or at least put him with someone with more experience (since last i checked that's how we train people, so i do find this annoying), but also i kinda found disturbing that you attacked this kid's vision esp on the whole gold vs. green severum. Yes he made a mistake with the JD and firemouth, that may have been out of plain nervousness, but did it ever occur to you that he could've been color blind? gold vs green it might've been all the same to him. Who knows, it may have just been out of inexperience and nerves, but do give him the benefit of a doubt. Afterall, it benefitted you in the end. Don't forget that you did happen to visit a petsmart.
I frequent petsmart all the time and when i do talk to their employees i make sure to let them know, i know my material and fish. I talk to them and share info if they don't know it yet because employees tend to care for all the creatures in general and there is plenty of room to make mistakes when you're dealing with 100+ species of fish, birds, reptiles and mammals.
The only way we can really progress in this hobby is by sharing info. If we keep it from other people, mistakes, mistreatments, and improper habits will just perpetuate itself from one so called hobbyist to the next. Just think of it when you visit another LFS or big chain store like petsmart. Good luck.