I think considering it's a new platform most people will use it for legitimate purposes but of course it can be abused.
What I will say though, that because it's voluntary to up-vote content or send a donation and it's decentralized currency, it may be morally wrong to mislead someone but it is your choice if you want to up-vote your content and waste your steem power on a post.
I guess it's why steemit is liked by so many because you can have somewhat of a say as to whether or not you would like others to see a particular type of content.