Explaining how server reputation works:

Server reputation is a numeric for how helpful you are to the server. The more you help admins by reporting rule breakers, jumping on explosives in the no-ex servers, playing from spectator, assisting the weak team, etc, the more your reputation increases. Committing infractions, breaking server rules, getting banned, etc, reduce your server reputation. 

Reputation is capped between -1000 and 1000, so it’s easy to get/lose rep early on, but harder near the top/bottom. Each command you issue, and every command issued against you, has a reputation amount; Some good, some bad. Every time your reputation changes, you are notified of the change in chat. Here are the different ways you can earn reputation on the no explosives servers:

Jumping on grenades/explosives. You are helping get problem players out of the server, so if you die by an explosive, you get reputation.
Issuing good reports on players. Just reporting someone gives rep, but when an admin accepts the report and acts on it it’s triple the rep bonus.
Reporting from spectator. Reporting from spectator is worth much more than reporting in-game. You are sacrificing your game time to help the server and should be rewarded. 
Using @assist. Sometimes teams really need help, and sometimes your friends are stuck on the weak team. Helping them and the server out by using this command to switch increases rep greatly.
Populating servers. Population mode starts when the server drops below 15 players. Any player who joins while the server is less than 15 players is placed on a populator list, and will be given 10 reputation if they stay in the server until it reaches at least 45 players. They are notified/thanked when the reputation increase happens because of this action. 

If you have infractions on your record, the negative rep they cause reduces over time, so you get some rep back for infractions on your record simply by not committing them. It does not reduce completely however, you will need to report some rule breakers to get it positive again.

High reputation has its benefits. 

> 15
Any punishment is reduced to a verbal warning. You still get an infraction point, and your rep is lowered afterward, but you will not be killed, kicked, or banned. This is to handle the case of shooting nade cookers, or accidental usage of banned weapons such as grenades. You should inform an admin of what happened immediately so the issue can be resolved, and your record returned to normal.
> 75
You receive report auto-contest. By now you are a trusted player, so any report against you should be investigated instead of simply acted on. This removes the possibility of you being falsely reported. Admins still see the report and can look into it, but can’t directly act on it without investigation first.
You receive a whitelist from the server SpamBot. Once you’ve reached this level of helpfulness you’ve seen these messages hundreds if not thousands of times, so seeing them more is just clogging your chat window. Enjoy!

To check your reputation ingame just type in !rep and you see your current reputation. 

NOTE! A VIP-slot doesn’t have any positive affects on your serverreputation!