I also know, as you know, that sometimes (or a lot of times), a knitter doesn't bother to knit a gauge swatch, and that often, it doesn't matter.
This is not the case in this story.
I cast on last month for a Tropical Lily for Baby Girl, using some Cascade Luna that I bought on the North Shore Yarn Crawl. I really loved the blues and purples of the yarn, and totally imagined how the colors would bring out Baby Girl's bright blue eyes.
I cast on the appropriate number of stitches using a size 7 needle as called for in the pattern, and I knit. I realized as I was knitting that the pinafore would be a little wide, but I decided that Baby Girl could always wear it next summer. Too big is always better than too small when it comes to clothes for children.
I followed the pattern, except to make a button tab instead of ties at the back. (I just didn't like the bulk of knitted ties). And, instead of putting buttons on the ends of the strap, I put the buttons on the inside of the waistband, and made 4 buttonholes on each strap, so the size could be adjusted as needed. Feeling very clever, I blocked the top, being careful not to add any extra width, but hoping to add a little length.
Unexpectedly, it is also ever so slightly too large for Little Girl. Thankfully, only slightly.
She wore it to school today.
The moral of the story: Sometimes, when you don't check gauge, it still turns out alright.
Happy Knitting!