They have absolutely no scent and are happy enough in my poor clay on the north side of the house. They also don't get much mildew (SLC is a desert, so that's not unusual), I rarely get aphids, and I haven't had any other pests or diseases in the 10 years I've grown them.
They begin blooming in mid-June and don't stop until the second hard frost, usually after Halloween. In warm weather, the blooms start out a lovely peach color and fade to parchment white, and the petals don't reflex back into triangle-points. When the nights turn cold, the blooms take on a reddish cast.
Like all roses in northern Utah, they died back to the ground in last November's hard frost, but as you can see in the first photo of the set (link above), they've come back vigorously. They haven't been grafted to anything. And they have only a few sturdy (!) thorns lower down on the canes.
Also, there's a lovely bit of japery in one of the photos' captions, even if I do say so myself.
They might be Eureka. I hope that California Sue pops in. She grows more roses than I do and Eureka is one of her favorites. I think it is a yellow floribunda. You can try searching www.helpmefind.com for yellow floribundas.
Another common yellow rose is Julia Child. I grow that one and I don't think this is Julia.
I think I have this rose, too. I got mine at a flea market in a 6" pot and thought it was a miniature just like you did. Mine didn't have name on it either, and it's now about 3' tall.
At first I thought it might be "Honey Perfume" but mine has no fragrance, just like you said. Mine also turns white as it ages.
I'll go look to see if mine's grafted...never thought of that !
No, I don't think it's Eureka, it usually has larger full blooms and while it tends to have touches of apricot when the weather is cooler, it is decidedly more yellow. Honey Perfume and Apricot Nectar have good fragrance as mentioned. Sorry, no idea.