I tend to agree with constlady, there seem to be differing definitions or applications of DADT.
For me it means the "dirty little secret" thing, which usually stems from denial. "Yes, have your boyfriends but I don't want to know about them, and I won't let you let it affect our lives" is one thing. Is that polyamory? Well, everyone knows about what is going on at some level so it's open and honest. Is anyone getting hurt? I think that the important thing there is to look at the reasons why it is put in place and to work out whether that is healthy or not. So it's polyamory, yes, but whether it is healthy or not is dependent on the individual.
The other application seems to be that of sharing the intimate details of your life with your other partner. That, too, has to be in individual choice, in my opinion. Part of the negotiation when a new relationship configuration starts can definitely be a discussion about how much of your relationships are kept private. Some people are a lot more "out there" than others about their lives - some to the point of blogging their intimate details. Some are far more private, and don't even want to share it with their other lovers. I think there is definitely room for personal preferences there and I don't see that as anyone being in denial about anything.
For us, in our current relationship, we know the intimacy level of everyone involved, but that is it - what goes on in the privacy of the bedroom (or whatever other place similar activities take place) is private between those in that space at that time. It works for us.
It's something that we have learned from experience - and I think that experience goes a long way to helping us make up our minds and form our thoughts about what we do, and don't want. I know I had a very different idea about it before getting into our first relationship, and the refining has continued over the years.
"Listen, or your tongue will make you deaf." - Native American Proverb