Would babysitting a well behaved dog help set a good example or creater more problems?

So my friend recently asked if I can watch their dog for an upcoming trip their going on. He is a fairly well behaved dog and I really don't mind looking after him (the more the merrier). I was actually thinking this could be a good opportunity.

My fluffer is very reactive at the moment, but this is directed at noises or when out walking ext. not with our cats or when his other dog freinds. Would taking him to walk with a dog who is not reactive multiple times a day help see he doesn't need to be afraid or would it possibly start rubbing off on the other pup. Just in general would having a calm dog at home with him make him more tense or mellow him out a bit do you think?