Are there expected dressing norms at faculty interviews? Will a casual tee-jeans be discouraged?
In the same vein, what is expected when a student visits the campus for an interview?
While its not mandatory to wear a suit for a faculty interview, it doesn't hurt, and may actually be expected in certain disciplines. Best to ask around beforehand. I've never heard of a dress code for student visit, but something semi-formal doesn't hurt.
As a general principle, it doesn't hurt to be more dressed up than necessary. The reverse can often be embarrassing. But as with most such thing, the departmental culture is the most important factor.
The only single right answer is that it varies.
However, there are methods that you can use to establish what the right answer might be in the particular case you have in mind.
Here's my method.
That's half the story. The other half is:
And if in doubt, wear the clothes that are smart clothes within the business world (rather than the academic world) in your own culture.
If you know who the person(s) you will meet with are, try to find photographs of them on their faculty pages.
The way they want to be seen by other people is usually pretty close to what they expect of you.