Never interviewed anyone face-to-face (the tyranny of distance here in Oz), but a few applicants for the last job I was on the selection panel for appeared smart over Skype, before we told them not to bother with the camera (we weren’t smart!)
If it was a face-to-face, I’d probably expect a suit, or at least a smart shirt, trousers, and shoes. Certainly if it was between two candidates, and one had made the effort, all else being more or less equal, the suited one would get it.
I have never actually had a face-to-face interview in science myself (was given both my postdoc positions, and my PhD just sort of happened), but I did don a suit for my viva, which was appreciated.