True!
Being a professional is independent of salary. Judgment, knowledge, discipline, ettiquette, and proffeciency are all a mark of a professional.
The argument comes in when you say that a professional appearance is independent of salary, it is not. Unfortunately, to look good... dry cleaned shirt, shined shoes, new pants. etc... a tad bit of income is required. So are work rules that allow for you to keep yourself "in a proper way".
If I'm making $16000 a year and only have 9 hours at the hotel while I'm at work, and two days a week when I'm not at work you can bet that my shirt will be wrinkled (I can't iron while I'm sleeping), my hair will be long (the paycheck has to stretch 4 weeks for a cut instead of every 2), and I'm going to buy food instead of shoe shine. It doesn't mean I'm not a professional pilot, and has no indication of my skill in the cockpit, it just shows that don't get paid a fair wage.