Thirkelgirl, I just watched Mean Girls for the first time with DD and the images of that "fun mom" are rioting in my head right now!! You definitely don't look like her, and thank goodness.
I'm with Echo, Angie, and Carla -- let's have a wider conversation about how/ why and whether we should be using terms like "mom," "mumsy" and the like to talk about fashions we don't care for. This is not about mud slinging. I fear I may have started this-- it was me who worried about looking like my mother "in the worst possible way" the other day! (Having said that, I also have fond positive memories of my mother's style.)
I think what we really mean to say is that some articles of clothing worn by some people imply a lack of effort or attention — a complete lack of interest in style. And as people who care about design and aesthetics, that pains us. But it's never really the article itself -- it's always how it is styled and who is wearing it. And it is all relative. On some bodies, capris are going to be more flattering than short shorts or bermudas (and vice versa).
This forum includes members in many different situations and with many goals. Some come after life changes (weight, job, new baby, move, etc.) needing some new direction for their wardrobe. Some have always loved clothes and fashion but it's never seemed to come together for them -- they have a mish mash of stuff that doesn't serve them well and they need to get a handle on how to dress for their real lives. Some have never ever felt stylish or had any interest really in style but have realized that this is costing them in some way, and they want and need help. Some are passionate about fashion and extremely knowledgeable and have a highly developed personal style. Some want to learn how to explore trends without breaking the bank. And so on.
Where am I going with all this? (Not enough coffee yet, ha!) I guess i am just saying that there is certainly nothing wrong with capris, ever, for certain people in certain situations. If you are hanging at your cottage with your kids and capris are the most practical and comfortable thing you can wear, then wear them with pride and put some effort into styling them if you feel like it (or decide to wear them into town on a grocery run). And look for great ones like the Zellas Angie pointed out.
And if you think capris look tacky on you, then don't wear them!
As others have said, the associations also seem dependent somewhat on geography. Capris make a lot of sense for some places and activities. Taken away from those contexts perhaps they make less sense, especially if not styled with any effort. But that is also true of shorts, skirts, crops, long pants, or really, any article of clothing!!
I don't think there are really too many hard and fast "rules." That can make it difficult to make decisions and means we have to train our own eyes.