My problem is the assumption that to be considered 'professional' you have to put on ridiculous airs like wearing a suit. Suits have no place in arboriculture other than standing behind podiums. Like Northwind said, it's an affectation, it's not natural for a person who works with trees.
We don't need to 'look' a certain way to raise the level of professionalism, we need to DO more, pay our people more and get reliable results. That means DIGGING and climbing and looking and cutting. Wear a suit to continuing ed classes if you want but I've never seen a guy in a suit excavating a root crown.
MDVaden is right, a lot of people think it takes a suit to be professional... because they either wear a suit themselves or they are stupid. Professionalism is about conduct and results, not appearances.
I don't trust anyone wearing a suit and tie to work... and I wore one for years. It became evident that the better dressed a guy was, the slipperier he was... less professional, not more.
I won't argue certification, it cuts two ways and if done right would be a genuine value. But I've met several 'arborists' with all kinds of certs that have never climbed, never seen a live flower high in a tulip tree, never experienced the differences in tree structure, never seen the canopy firsthand... get all the certs you want but if you've never climbed, you aren't an arborist, find another job title. Hell, maybe 'Certified Arborist' should be reserved for guys who read about trees more than they touch them.