just because you get flagged doesn't mean that your content isn't good.  In some cases it means that an investor is worried about the reward pool and thinks that you are getting too much from the pool.  
In another case, it was that the whale in question didn't think that a certain type of content belonged on Steemit.  

In both cases, I can sort of understand it, but if the reward pool is so small that one whale loving a post breaks it, then the reward pool needs to be bigger.
Also, if you get flagged, another whale can upvote you, which should negate the downvote.  But I'm not sure if you'll get the funds back.
All I can say, is keep putting out great content and the occasional flag won't bother you.