There are actually two types of contents that I upvote.
The first is content that I like, and the second is content that I don't like, but which the author has obviously put efforts in. Because I may not like the subject, but I appreciate that the person has put efforts in creating content that holds a certain quality. It's already hard for people to grow an audience, and even posts which have a certain quality won't even reach 0.10 STU.
In some ways, it's even more discouraging than getting nothing because it means that your efforts are "only worth so much" and kind of devalues the person. To me, it's one of the reasons that some people just rage quit Steem, along with Steemit"s attitude of playing against Steem's interest. Their regular dump devalues steem, and it somewhat kill us all at the same time.
That's why, no, I don't mind upvoting content that I don't like. Upvoting is more a matter of supporting a person/blog in its entirety, than specific content. It's not like a thumbs up in facebook, it's a matter of saying people that their best isn't "unworthy" and a meager attempt at respecting them as a person.