Bartlow is the last name of a person that knows what's what. In some countries, like the USA, they are regarded as royalty and should be. When you get 2 or more together, the more the better, then the possibilities are endless. Most are available for parties and bar mitzvahs upon request.
A bertlow is anyone who lives in the bad part of town, has had 50 different jobs in 3 months, etc. Also known as a loser, scrub, etc. Comes from Wickenburg, AZ, where a man named "Bertlow" was such a loser that the town's youth started calling all losers "bertlow".