Check users can check your IP and account and all those stuff. If your IP matches with two accounts or more, then you're basically fucked.
Don't resort to sock-puppetry, or they'll get ya!
Unlike with wikipedia, there aren't 150 billion rules governing your use of checkuser. However, some basic common sense is expected to be observed:
- Do check for socks if common sense says two accounts are probably linked
- Do check and IP pwn spambots
- Do not check random users as a "childish prank". Block, delete or remove user rights if you feel like abusing your power, but much like 17 year old virgins this is strictly off limits, k?
Remember that all actions are logged and if you're caught being an ass with it, you're probably going to get your anus resized to the width of a dinner plate.