Thank you all so much for the thoughtful and insightful comments, I really enjoyed reading everyone's thoughts on this idea! I didn't mean for it to sound like I only use happiness for oddball items, I do use it for everything
/highfive to my kitty shirt twins in navy Tanya and Una (I must see this outfit, Una!!)
Denise and Tanya, yes I hear you both on not wanting to limit myself. My "definition" isn't a rubric, or even something that's remotely straightforward. I have a few different definition systems that each cover a different style aspect and then I cross the lot to make determinations. It's complicated but works well for me, and is actually rather open-ended in many directions. I think this type of open-endedness is necessary for those who wish to be trendy; it's just not possible to incorporate enough new trends otherwise.
Hil, I think it's perfectly fine to have more than one style persona as long as you don't feel overwhelmed by it. Though it can certainly be challenging to marry very different personas at first, and having an overarching sense of the vibe you wish to obtain can be really helpful.
Ornella, Rachy, and Cheryl, I certainly do apply happiness quite strongly in daily styling as my mood is very strongly affected by what I am wearing. But as someone who doesn't really love to shop (it's OK but it's not my favorite thing, though I am starting to like it more again) AND who likes a LOT of styles, I just really need to find ways to keep myself focused. It's not enough to LIKE an item, it's not enough for it to just fit my style goals, and it's not really enough just to be happy; it really needs to be some combination, but happiness certainly gets a VERY heavy weight. More and more I am finding that if I force myself to be strict up front, then when it comes to styling the items that make it into my wardrobe I'm happy as a clam!
Harmonica, good observation! If we are happy and comfortable with what we are wearing because it is true to us, it will certainly add to an air of confidence which helps make those outfits seem effortless.