Mint packages browsers to make money off of them, including the very questionable use of OpenDNS advertising pages as fallbacks for hostnames that are not found.
I'm wiling to tolerate that just to not have to put up with Unity malarkey. Besides that (though I haven't tried 15 yet), I was able to dual boot 14 on my old Dell Inspiron 8200 and use it as an OK browsing rig. This was intolerable with Ubuntu.
But it is similar - if you use web applications in your every day life, then a misspelling may well send your misspelled info to Amazon, if they advertise through OpenDNS (though I'm unfamiliar with how OpenDNS works).
The way you put it makes it sound like you're locked into using OpenDNS.
I have used OpenDNS before and while I didn't like their ads in place of not found hostnames, it is part of their revenue model and they have to make something back for what they provide. It seems a reasonable exchange for a free service.
I presume LinuxMint has some sort of partnership with them, but I don't see this as being evil, considering they also would probably want to make some money off their custom distro/work they put into it.
I appreciate the work that distro maintainers put in, and I understand that many would like to earn revenue somehow from the distribution. If you give us the option to opt-in, then I'm fine with that being part of your revenue model. The fact that people have the option to disable a feature doesn't make it any less sneaky or inappropriate to put in (in my opinion).
I don't really understand how it could be interpreted as 'sneaky'.
I think what truly might be bothering people is the fact that someone out there is just trying to profit off of them, some through less/more sleazy ways than others.