Junky's -> ownership
"The Junky's phone."
Junkies -> plural
"Junkies and texting..."
Not trying to nitpick, but a dominant word in your post is a grammatical error on your part and yet:
I just don't get it, I'm a junky, and I text with good spelling, grammar, and above all else, my texts make sense!
So maybe I am trying to humble you a bit. The first word of the title of your post contains a fuck-up. Irony? Or maybe you're just like a lot of other people, where you don't have all of the answers for all of the grammatical situations in the English language? If it's the later, it's totally okay! Just be ready for criticism if you're going to expose yourself like this! I'm sure that you're a better writer than a lot folks out there. But at the same time, others might not make the mistakes you do, so don't get overconfident, my friend.
Some people really struggle with the English language, others excel at it and then most of us fall somewhere in-between. Do we intentionally sometimes operate at a level that is lower than what we could optimally test at? Sure. But why? Maybe we're doing it as a joke. Maybe we're impersonating another person who's not that great with typing. Maybe we want another person to think we're less intelligent than we really are (for any number of reasons*). Maybe we are really fucked up on drugs. Maybe it's dark in the room and the girl you brought home from the bar is nagging at you to come back to bed. Maybe you dropped your phone while on drugs and now some of the keys don't work properly? Maybe you handed your 9 year old the phone and told him to send a text for you, as both of your hands are covered in cake batter? Maybe English isn't your first language? The list goes on and on...
*I had an old dealer tell me that he intentionally would text like an idiot so that people would underestimate his intelligence.
So you're saying that there's a correlation between bad texting skills and heroin use? Perhaps, a lot of users probably do, on average, have less education than non-users and/or have less up-to-date technology available to assist their ability to use the language well (so we could make the good ol' socioeconomic argument). And then heroin users are often under-the-influence, which (unless you're Charles Dickens smoking opium and writing next to candlelight) isn't going to exactly
improve your writing skills. Heroin casuses apathy too, and a lot of people probably just don't care if their texts would pass or fail a formal grade in an English course. As long as their skills are sufficient to the goal of obtaining more heroin and keeping the habit going, there's often not going to be a burning desire to try and text better.
Now if you'e trying to say that heroin use
causes people to become worse texters, at best the answer is probably "situationally, perhaps." What I mean is that using heroin (negatively) affects your brain's ability to perform a lot of functions that require advanced thinking. And though using a language is advanced thinking, it's typically so ingrained in us already that heroin's not going to affect our ability to structure sentences, spell correctly, know how to use grammar rules, etc. much at all. It jusssssssssssssst migt maaaaaaakkkkkkkke this shiiiit happn
In my experience (in a first-world country where use isn't as rampant in young, young kids as in other countries), most people obtain their level of English proficiency that they will carry through adulthood well before they really get caught up with heroin. I've met some really good writers who are hopeless addicts (I consider myself to be a good writer, and people actually make fun of me for using proper English always in text-messages), I've met some good writers who would NEVER think of doing something as pathetic and selfish as heroin (

), I've met some people who are horrible writers who do heroin, and then I've met some horrible writers who don't use the drug. Throw in how it's often "cool" to type in weird/strange ways these days, and how these evolutions of the English language for texting and/or online posting tend to transcend things like whether a person does or does not use drugs/heroin, and I don't really think that there's a noticeable causation between using heroin and your ability to text well going down the drain.