I only have 2 pairs of work pants and I dry-clean them every 3 months. The blazer also gets dry-cleaned every 3 months (at least during the colder months when I actually wear it). I take one shirt per trip, and don't take an extra. If I spill something on it, hopefully I have a blazer or trench coat to cover it up while I'm in public. I bring a fresh undershirt (full size white-T) for everyday, so the sweat usually isn't a big problem.
I've only had one captain so far complain that I smell. That was on the 4th day of a 4 day trip with the same shirt on. On the first day I prespired quite a bit because I had to do some jogging thanks to a 15-minute callout from scheduling while sitting airport standby. That capt. also complained that my shirt was too wrinkled, but he promised not to put that in my probationary pilot report. Thank you sir.