This is a pretty important aspect of microbiology: necessary to avoid contamination, or cross contamination; good old observation of strict aseptic technique.
Now you don’t necessarily have to observe strict protocols or even adhere to ‘strict’ aseptic technique, but if you are advised to work around a bunsen, flame tweezers before use, flame lids and keep tip boxes closed between use, then you’ll probably avoid most contamination risks. Well if you don’t listen, this is what you end up with..
I’m pretty laid back about working habits and don’t get contamination, but I’m also impressed that it’s even possible to get this much contamination.. Oh well, positivity..that’s what they say right?!