The lesser of two evils?

When I don't like someone (or when I disapprove of their conduct), more often than not, the object of my dislike is often unaware of my feelings towards them, unless they are a very very close friend (to which I would have few qualms coming out with "What do you think you are doing!?!?!" because I know that they know how to take me). My rationale is that well, it's merely my opinion on them, and I do not claim to hold the ultimate and deciding opinion on them- I'm sure there are many other people out there who think they are perfectly fine- no need to subject them to what is merely my opinion about them. For all I know it could be totally the wrong idea anyway.

However, some people are of the opinion that if you don't like/disapprove of someone you should make sure they know, and I can see how the people in this camp might think that the position I adopt is hypocritical in that a lot of the time I'm just acting pleasant, even though they irritate the crap out of me!

To which I would say...is there really any point in pursuing such a course of action?? Won't it just make things worse to bring antipathy out into the open? What could be the best possible outcome of making sure it's very clear you don't like them...probably just that they don't hassle you anymore. Which wouldn't be such an ideal outcome if you don't mind them at arms' length.

And besides, it's not like not liking someone is such a noble thing that it is to be flaunted around! Methinks it's better to at least try to be civil to them, and maybe in the process forget about what irritated you about them in the first place!

But then again, do you think the object of dislike/disapproval would rather know that you just didn't like them in the 1st place?

Which is the lesser of 2 evils??