Did you mean to post this in the Note 7 forum, when the Note 6 isn't even out yet?
It depends on what you mean by unlocked phones. An unlocked phone that was never meant to be sold by a carrier won't have any of the carrier bloat, although it may still have plenty of manufacturer bloat. But a phone that was originally sold through a carrier (and therefore has all of the carrier bloat) can still be unlocked, and therefore labeled as "unlocked" in a sale listing.
If you get an unlocked phone, you have to make sure that it supports the network bands that your carrier uses. You can find this out by looking at the phone's specs in the sale listing, and then cross-referencing with the carrier's bands (search the web for "[carrier name] network bands."). If there's overlap, then it should be as simple as buying a SIM card from the carrier and inserting it into the phone. Make sure the SIM card size matches what the phone takes, since there are a few different sizes.
What I described above is how it works for GSM networks (like AT&T and T-Mobile). It can be a little trickier with CDMA networks like Verizon and Sprint, since the CDMA network doesn't use SIM cards--it requires the carrier to activate the phone.