I have come to notice so many people write or type ~mostly type in such strange fashion.  Some do it because they think it is cool, but to me, it's almost illegible.

Shorthand:
While shorthand is great for people dropping down notes in a hurry, do they have to write like that in "real-life"?  You may think it's easier for you to write, but it may take a reader twice as long to read!  Now, I am not pro-conserve the "old-fashioned English".  I accept that languages would change, and they do.  Over time, new words are invented or re-defined to suit that particular era.  But, people nowadays just basically invent an entirely new alphabet system.

New Alphabet
I am not an expert at this "new language", so I can't list out the new codes.  One time, at our school, there was a Student Council Election, and this candidate actually wrote his campaign policies in this "new alphabet system". ~I don't know what it is called.  So, hoping to see his views on some of the key issues, I attempted to deciper his codes.  I stood there for 5 minutes, staring at the poster, and I concluded that I couldn't read it, and gave up.  The only "new information" I walked out with was his name.  But that could be from his other posters, with legible words.
T l-l l 5   l 5   4 ll   3 )( 4 lVl  P L 3.
It is horrible trying to read it.  In case you can't tell, it says, " THIS IS AN EXAMPLE".

Capitalizations
There are some people who think that it's also cool to write in capital letters,  although, they would not write all letters in either upper or lower case.  Instead, they would cHoOSe tO cApiTalIzE wORdS in A RaNDom FasHiON.  Please, by writing like this, you are causing numerous people to read at a speed 3x slower than normal speed.

Spellings
I will admit, I am guilty of spelling errors.  But, some people, they are such terrible spellers.  So, they write in homonyms (words that sound the same but are spelled differently, eg. marshall and martial).  I can't speak for others, but at least, for me, I can't understand homonyms.  I interpret words according to their meanings, not by how they sound.  This creates a bit of a confusion for me.  Like in one case, the author of an Internet post writes, "and he succeeds the thrown."  I couldn't understand it for 1 whole minute, because nothing was thrown around. In the end, I realized that she meant "and he succeeds the throne."  Now, I am sure there are lots of people who would understand sentences or paragraphs written like this, but I can't.  Same thing with the substitutions of the sound/letter of "d" with "t" or "th".  Something I often come across is people saying, "U r da bomb," or "dis is... dat is ...".  Again, lengthen the reading speed.