Yes, Melon has rumbled the dirty little secret ('dirty' secret based on her facial expression in panel 2) to identifying what is the location you're about to enter! I'm sure that Arthur will be most impressed with her achievement!
I have the feeling that the great chemical difference between tea and drain cleaner will mean that Melon is in for a very,
very bad trip. I've got the feeling that she's going to hallucinate a horrible Cthonic monstrosity and then complain to Emily that she "didn't want to have to explain again to Charlie why I dumped him!" or something similarly other-worldly.
It looks almost like Melon was activated (woken, brought on-line, made conscious, however you want to describe it...) with absolutely no background knowledge of the world into which she was being unleashed. In other words, a complete innocent, bumbling through a world full of hazards - it's a wonder that (so far) she's only lost her butt!
I think that it's more the case that she makes absolutely no assumptions about anything. Just because apartments have numbers on the main door doesn't mean that it is the apartment's number. Just because there are names painted on the outside of shops doesn't mean that this is the name of the shop. She is having to verify that empirically on a case-by-case basis and I don't think she believes that it is a universal rule!