I can't believe anybody would use the "Urban Dictionary" as as point of reference unless it was to be a throwaway line or joke. (Granted it is a perception but only applied by members who 'think' they are the 'upper class'. It certainly is not the perception used by the vast middle class.)
Basically, Trailer Park Trash is a term that is commonly, if erroneously, applied by certain members of the public (those who were born with silver spoons in their mouths or, at the least, their parents were) to another less advantaged group. It is often interchangeable with the term redneck as trailer parks were more visible in the southern states in the days when they first started to dot the landscape.
Trailer Parks were a way for the less educated to own their own homes for thousands of dollars and not 10's of thousands of dollars. They parked (another misnomer) these behemoths, some of which were 80 feet long or more, in lot's where they paid ground rent and had sewage, power and water facilities to the lots put in by the park owner. They became small communities. Unfortunately, but perhaps expected, they were lower educated and smaller earning taxpayers so tended to be a colorful mixed bag of people from the "underbelly or working class" as opposed to the higher educated who gave them the nickname.
Today, like the word 'redneck' it's almost a badge of honor. Some of the Doublewide trailers seen today would rival a lot of middle class homes at a lot less cost. Unfortunately, when over here in expat land, it's the trailing spouses who tend to like to portray themselves as having the same living style back home as they do here. Anecdotal evidence does not seem to support this on a wide scale, although admittedly they do exist, especially among those who spouses are in the Financial Industries (that may well be changing and they may well be joining the ranks of "trailer trash" when the current shakeout is finished).
Often, I have to wonder at their "original" backgrounds. I wonder how many of them actually married above their stations the way they devoutly protect their 'current' positions. it's like they are afraid of returning to their 'past'. That's one that is practiced here in Asia all the time.
The term 'Trailer Park Trash' or 'redneck' in the US today is more like the term Ang Mo here. It's early usage was derogatory in usage but today is a tolerated, even if un-PC term that can be cutting or friendly depending on how & when it's used and between different segments of the population.
As a farmboy, some might/do class me in the same lot. Fair enough, it really doesn't bother me. I don't have the education that most here have. I, like most of the underclass, had to "work" for everything. Maybe having to work for it makes me appreciate it more. However, perception and net worth are two different things aren't they.
Did I get here by luck? Yeah, you could say that. Thanks to all the "highfliers" back in the early '80s causing the US Oil Embargo, and shutting down most Oil Production in the US provided me an opportunity that I jumped on. Thanks Highfliers for providing me the "luck". But, like anybody, I tried to make the luck work for me. Luck can also mean when one marries the right person who is able to give you the lifestyle that you 'think' you deserve. Without that person to pull you along it could be an entirely different journey. So, if you are not the one who is providing the opportunity, then you can thank your lucky stars that you were lucky enough to seduce or be seduced by that spouse in the first place!
Does that make me less a person? Nah. At least I don't have to put on airs like some do (even on this board). What you see is what you get. I'm real. Abrasive? Yes. Honest? Yes. Able to butcher the English language? Most definitely. But when you scratch the surface, I'm still the same underneath as well. (which is both good and bad as my wife will attest!)
Nobody knows what fate may present in a slightly different set of circumstances. To believe you would be in the same place if things had started differently is rather naive from my way of thinking. Karma? Nah.