Inspired by this thread, which was closed by Tuba for obvious reasons:
What I mean is, isn’t it enough to just compose whatever you want, then just hit “preview post” to see what the final product would look like?
Unless a poster is demonstrating a groundbreaking new way of styling font or introducing a new smilie, isn’t it kind of silly to go ahead and actually submit the thread?
I dunno . . . maybe a vestige of the days before we had preview.
For some it’s a way to test functions they aren’t familiar with.
For others, post padding? No, of course not! No one would EVER do anything like that here!
And yes, preview is your friend, in more ways than one.
TubaDiva
Actually, here’s a thought - can the board be set up in such a way that the ‘submit’ button is disabled in the first instance until a thread has been previewed?
Think how much time could be saved in fixing coding errors, and how many ‘test posts’ we’d be able to avoid! 
It bugs me when I pop into ATMB and the front page is mostly ‘Test’ posts. Not enough to make a Pit thread - yet - but it really is pretty irritating.
Some message boards don’t have an immediate submit button - just preview button, and then on the preview screen you get a submit button. But hey, if posters were given the chance to rethink their posts, what would we need the Pit for? 
The thing is, there are reasons why to post a test, for example in my thread on Webdings:
http://boards.straightdope.com/sdmb/showthread.php?p=7124583
Besides testing how the Webdings font works, the reason why it is posted is to test if Webdings shows up in different platforms, AFAIK it should work in Windows and Mac OS (over 10.0 on Macs)
Because I posted, then can later confirm that it is not working on my Palm Clie machine. If the graphics are not showing, you are invited to post your computer specks.
BTW, that last request would not be possible too if one was just testing using preview.
Well, yeah, but that’s hardly the usual Test Post, is it?
GIGObuster, assume special fonts don’t work. There are too many issues with getting them set up on even ‘user-friendly’ computers, because they often need to be downloaded (an act of questionable legality in most cases) and placed in special directories and incanted over by programs unfamiliar to most users.
Besides, it’s pretty common for people to view webpages with a browser set to not allow people to go changing fonts around on them. Being treated to a page in 9-point Comic Sans is an experience many people can easily live without.
Also, the preview window allows more characters per line than does the published SDMB window. This affects text layout. It’s the only discrepancy I know of between the preview version and the published version. Not that anyone cares about the number of characters per line, normally, but it might make a difference if you were posting code and had to get all the characters to line up just so, and were using really long lines of code.
OK, so we all know that “preview” functions like a new post. Now ask yourself this: How do we know this?
Well, if I click “preview post” before I close the refrigerator door…
Galileo?
But my point is, if the OP is only experimenting with different font colors/sizes or trying out a spoiler box or any other kind of basic coding, the preview screen would show that it had been done correctly. Then, there seems to be no need to go ahead and post the thread.
Even if someone is trying to create a practice link, that link can be followed from the preview screen. Thereby proving that the coding was done correctly.
Not that I mind seeing all the test post threads (such as the webding thread or the one that taught me how to do this spoiler box).
Webdings
1234567890-= qwertyuiop[]\ qasdfghkjl;' zxcvbnm,./ Shifted WebDings ~!@#$%^&*()_+ QWERTYUIOP{}| ASDFGHJKL:" ZXCVBNM<>? Wingdings 1234567890-=
qwertyuiop
qasdfghkjl;’
zxcvbnm,./
Shifted WingDings
~!@#%^&*()_+
QWERTYUIOP{}|
ASDFGHJKL:"
ZXCVBNM<>?
Wingdings 2
`1234567890-=
qwertyuiop[]\
qasdfghkjl;'
zxcvbnm,./
Shifted WingDings 2
~!@#%^&()_+
QWERTYUIOP{}|
ASDFGHJKL:"
ZXCVBNM<>?
Wingdings 3
`1234567890-=
qwertyuiop[]
qasdfghkjl;’
zxcvbnm,./
Shifted WingDings 3
~!@#$%^&()_+
QWERTYUIOP{}|
ASDFGHJKL:"
ZXCVBNM<>?
Symbol
`1234567890-=
qwertyuiop
asdfghjkl;’
zxcvbnm,./
~!@#$%^&*()_+
QWERTYUIOP{}|
ASDFGHJKL:"
ZXCVBNM<>?
It is generally not necessary to toast pests, either, but it is amusing to watch them shrivel in the heat.
I think we’re done here.
TubaDiva