There are 2 sides to this.
One side feels that a certain level of respect should be give the ceremonies. Many lodges expect officers to wear formal clothing, i.e., tuxedo, and members to wear suits. Only informal occasions such as outdoor or cave degrees would allow informal dress.
The other side is in the "we don't care what you wear, just come," faction.
Having seen a WM struggle to get a junior officer to dress in something more appropriate than sandals, cut-off denim shorts, and T-shirt, I asked my officers to at least dress in collared shirt and trousers.
To answer the original question, I would be a little evasive: The FC candidate's coach should have taken care of this beforehand!
S&F