Reputation is a member to member aspect. Thus we do not edit it, unless there is some sort of abuse of the system. (Rep for rep, begging for rep, trading rep for thanks etc etc.)
Most members + or - Rep you depending on your behavior, tone, and deeds. Not all are fair, some just like to see people further into red. However apart from a form of feedback, Rep has no significance, and determines nothing about the user, as far as Applications, Trades, sales and buying goes.
If people do accuse you of scamming, without any sort of evidence, report them, as this is against the rules.
If you do good deeds, are helpful, and post original content, asking for rep in return is allowed. So long as you do not use it as a tool. IE: "Hai guise + rep me 5 times and you will get a hack"
That is not allowed. However adding " If I've helped you, or you enjoy my content, please take the time to +rep me." That is allowed.
Hope this info helps, and don't worry about Reputation so much, like I said in 90% of cases it is meaningless.