Six years ago when I was in Bangkok I upgraded my return flight back to Hawaii. I went to the airport and was sitting on my backpack in the business class check in line. An employee came from behind the counter and and said "you are in the wrong line, coach is down there" and pointed. Well I very quickly whipped out my business class ticket and assured him I had read the signs and that I was in the correct line.
For this trip I also upgraded my economy seat to business class using frequent flyer miles. (well worth the 15,000 miles it takes). I am curious if I get the same reaction this time, I have the exact same backpack, same dreadlocks and all in all look like a poor backpacker and not somebody who fly's business class.