Every social system must have provisions such that users cannot game it. It is a fundamental goal of the system design.
At a very high level, we can take two approaches to achieve this -
Make it extremely difficult for someone to game the system. Example - Google. Google spends tremendous amount of energy on ensuring that people do not game the system.
Reduce the incentive of gaming to zero. Example - Wikipedia. If you put some spam on Wikipedia, chances are that the very next person who visits the spammed page will revert your changes. End effect, only one person saw what you had put.
We know now that the first method is not fail-proof. Wherever money is involved, people are able to spoil Google results and the search results are more like advertisements. Even though you may see that these are not good results, you cannot do anything about it and those bad results will stay on the first page for a long time.
So, with Google, it’s hard to game the system but once you have gamed the system, the incentive is very high.
That’s not the case with Wikipedia. There, gaming the system is extremely easy. As easy as it can get. Just edit the page and put an advertisement for yourself. But there is virtually no incentive in doing so. That’s why Wikipedia has very little spam compared to Google.
So, what do you want to do for the system you intend to design? Make it hard to game it or remove the incentive of gaming it?