I am not sure if your question was serious but I recently found out that you cannot lose more than a certain amount - I think it is 5 - karma on a single comment. So if you make four shitty comments you can only get up to -20 on your user page. Or at least it's something to that effect.
Although adding onto what fatswimdude said as well, you can just post cool memes and make your posts look nice and get at least a few points.

http://www.reddit.com/r/truetf2/comments/3qbake/tf2_meta/
Do people think the bans and restrictions are just arbitrarily decided by the TF2 Gods?

Nice meme, dude!

It's pretty much a lost cause to promote any kind of "serious discussion" on reddit without having any memes thrown in. The only real subreddit that can accomplish that is /r/askscience, which literally has at least 400 moderators.

Actual content:

http://i.imgur.com/f2MFDJn.png

http://i.imgur.com/aaCrVAT.png

http://www.reddit.com/r/truetf2/comments/3nlfac/why_is_the_ambassador_allowed/?sort=confidence

I like how even with that costume of all things people in the comments section are still saying "eh it's better than what I could do"

I found that to be funny

The post is less cringeworthy than the OP's own comment:

http://www.reddit.com/r/truetf2/comments/3mvq95/should_comp_medics_use_a_jumpcrouch_script/
Imagine not being able to press two buttons at once.

http://i.imgur.com/bllP2hT.png

Projectiles that don't travel in a straight line? Oh no.

http://i.imgur.com/idoGZv3.png

Surely posting this on every loadout picture won't get old quickly.

YouTube comments are such low hanging fruit, they are in the ground.

http://i.imgur.com/ZlKNqIm.png

http://i.imgur.com/s8jP3rX.png

Redditors take a poll about random crits.

http://i.imgur.com/lMY07oV.png

http://i.imgur.com/xo4HERO.png

The top comment explains it pretty well.

Pretty much a gimmick account gone too far.