What does XP even do? I dont get it and i cant see where it says what it does anywhere.
So true, although sometimes it's hard to judge whether your post is spam or not. Are short comments always spam?
Not spamming - just posting short messages in posts also gets counted as spam for some reason 
oddtrans, you need XP to be able to get for example a random Steam CD key, you need level 3 in order to do so, also levekeing up to three and further will earn you soul gems
Maybe this is the reason why the experience earned is decremented.
in 3 steps
Choose the game that interests you and play itfor free.
Every game has some quests for which you will receive Soul Gems.
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
You know that on Gamehag you can get real rewards for free, right? Join us, complete walkthrough and get your chest!
I recently learnt that by spamming in the forums you might get the exp quick but you will lose it all because people will report you for spam, so instead make quality posts that are actually interesting than spam.