No, I have never whitelisted a site, at least not permanently. A few times I've temporarily turned the blocker off and given the site a few clickthroughs to support them, but after that, it goes back on. The ads are simply too intrusive, resource-heavy, privacy-invading, and potentially unsafe to do otherwise.
If the ads were simple little inline things that are hosted on the same web server as the site being visited, with no tracking cookies or scripts in use, that would be one thing. This would be most like the print ad analog. That's not the norm, though; most ads come with a heavy dose of tracking/analytics scripts that bog everything down, waste bandwidth, destroy privacy, and retrieve ads from remote servers that could be hosting malware. An average web magazine type site can have dozens of analytics, tracking, and advertising scripts running all at once (I've seen more than a few that have had more than a hundred third-party domains blocked-- for a single page). Open a few dozen tabs and even a fast PC can get bogged down, and it's even worse if you have a mobile device but you still prefer the desktop (full) page.
For those sites that try to force the issue with whitelists, there are anti-adblocker countermeasures. The combination of the ones in the list of uBlock Origin and the one I use in GreaseMonkey have so far vanquished all of the paywalls and whitelisting demands I've come across. I'm not permanently whitelisting any site... I may do it for a test here and there (to see how it works with nothing blocked for comparison), but that's it, and the cookies get cleared afterwards (and my IP address changes day to day anyway).
Guilt? No, never; why would I? It's self-defense, and I resent the site publishers for making such unacceptable web sites that I have to configure and use all kinds of add-ons to try to undo their ignorance, negligence, and maybe even malice. If they didn't try to use my bandwidth and my CPU cycles (for which I pay the electric bill) to track me in defiance of my wishes and send them personal information I don't want them to have, I would not have to block their ads in the first place.