Casual  
Business attire  
Gym clothes  

It's funny when I get to a client's super nice apartment (say it's the weekend) and they are waiting in basketball shorts and a T-shirt because they've been lounging. No shame in that!

Lol
I recently had my first outcall to my home and was kind of freaking out on what to wear.  
The first time she came to my house, i just got home from work.  

A sport shirt with a collar that buttons, dress slacks, sports coat, and shoe made of something that had parents.

The time of day, where I am either going to or coming from, my stated reason from being away from others.

out call ... depends on who and my intentions.  
If its my ATF, she may find the doors open and me in the shower or gym shorts, soon to be sporting a boner.  
If its someone I'm seeing for the first time, in or out, I dress to impress but never ostentatious, that's just not my style.  
I usually prefer no underwear.