I have been interviewed lately and during the interview a client told me that he liked my interview dress code. I was quite surprised since I had nothing special but a polo-shirt. I asked the client why he complimented my outfit since I was not wearing a tie, and he told me that his previous interviewer appeared on Skype interview in his undershirt (!). I was interviewed for a position which required a very experienced individual so I was surprised by his statement even more.
How should a freelance candidate be dressed for a freelance Skype (or any other similar conferencing app) interview, and how can one tell what's appropriate and what isn't?
I am here asking about Skype interview only, not about meeting the client face to face.