Its very hard to know that for sure... and yes, that can be a problem for some things... but that's why there is curation on Hive. Accounts that are not trusted, don't get as many upvotes, and the ones that have good stake and are doing what the community wants or other stakholders value, get more upvotes for their content.

Its very simple. And therefore why creating a reputation on Hive is so valuable.

Keeping on doing deceptions has no long term value. So that for itself, will die over time