The essence of this is you need to decide the answer to two questions:
1. What are your personal ethics?
2. Who do you trust?
To put (1) in context, the content on the Internet is largely provided free but is ad-supported. When it comes to display advertising, it's sold almost entirely on a CPM basis (it may be resold on an eCPC or eCPA basis). It is at best only partially sold on an intent basis (meaning it's enticing you to click on the ad or otherwise take some kind of action).
The relevance is that the most common "defence" of ad-blocking is "I never click on ads anyway". While that might be true (let's just say that the people who claim to have never clicked on an ad is a proper superset of the people who have never clicked on an ad) it's also irrelevant since that may not be the intent and the publisher is getting paid to display the ad, not for you to click on it (unlike, say, search advertising, which is intent based).
So the ethical part here is you need to decide if you're OK with denying publishers income yet still consuming their content. If you are against ads for whatever reason and don't consume the content, that's a position I can respect, otherwise it just strikes me as rationalized freeloading but YMMV.
As for (2), the big players like Google who dominate display advertising are regulated and deeply concerned (believe it or not) about privacy and the user experience. That's why you can opt out of personalized ads [1], for example. I may be biased [2] but I trust Google far more than I trust some fly-by-night operation. Again, YMMV.
Recently there was a story about Ghostery reselling user data to advertisers [3]. How much can you really trust these basically unaccountable groups (in comparison)?
I should point out that there are two issues here that intertwine:
1. Ad-blocking;
2. Privacy.
My personal code of ethics is I don't block ads because honestly I mentally block them out anyway. Going to the Westin site then seeing ads for the Westin everywhere doesn't particularly bother me.
If a site has particularly egregioius ads (I include popups, most interstitials and any ads you need to dismiss in this category) then all bets are off. Block away. Banner ads however? Sure, why not?
But where I draw the line is with uselessly giving away your privacy in a way that doesn't benefit publishers at all. I include all the various "Like" and "Share" buttons here. All of these track for no benefit to the publisher (other than the hope that you might use one).
Those I'll happily block. Likewise if you're Quora and you blur answers because I'm not logged in with Facebook, well you'll get technically circumvented as well and I may just block any ads you have just because you're being offensive.
Anyway, just consider that ad-blockers have access to a wide range of your data as well and ask yourself what they are doing or might do with that data. Is it really worth denying publishers income to not see an ad for shoes? Really?
[1]: http://www.google.com/ads/preferences
[2]: Disclaimer: I am a Google engineer working in display advertising
[3]: http://www.lifehacker.com.au/2013/06/ad-blocking-extension-g...