I will forget if I wait for a litter, but I took one of the pinks from this one and grabbed a couple of quick photos and just drew on them
So here is a mouse pinky head- a clean photo and one with markings. green is the skull, the blue are the eyes, the yellow is the whisker beds. They appear redder in the first image because there's no bone beneath the skin.
A good whisker bed will be broad, making the face appear rounded at the tip instead of pointed. The red arrows point to the rear of the whisker beds, where they join the rest of the face- the "base" of the bed.
The base of the whisker bed should not pinch inwards, as shown by the blue outline. You want a nice, broad base that blends smoothly, like shown by the green line.
You also don't want the whisker bed to be narrow/flat to the skull- this leads to a mouse face that is super pointy. I didn't draw lines for that but here are three different mice from my bins to demonstrate how these translate into adult mice.
First photo- flat whisker bed, pointy head shape. Second photo, pinched whisker bed, hourglass head shape. Third photo, wide whisker bed, smoothly contoured head.
The last is the goal for show-type mice. It's not a problem for them to have the other shapes, like there's no ethical consideration between any of these, which is why it often takes a back burner in my mice as one of the last selection qualities. If I have two mice who are "all else being equal" (equally good in all other qualities), then the better whisker bed will win to remain as a breeder. But, personality often wins first.
As for tails, this can be trickier on pinks, because the shape of their tail set can vary GREATLY depending on what their legs are doing at the time. Ideally, you want to gauge tail set when the pink's feet level under them or kicked out behind them, but the mouse is relaxed, not trying to move forward or backward. Moving forward can make the tail set look better than it really is, and moving backward can make the tail set look worse than it really is. So bear that in mind.
Here is a mouse pinky butt, in a relaxed stance with the feet under her.
Ideally, you want a thick, long, smooth lead out of the rump to the tail, as shown in red. However, a lot of mice have box butt, where their rump is flat and their tail looks like someone just jammed it on there, like with the green outline.
As you can see, mine are middle of the road on this- they could use better rumps, but they're not flat assed either. You want this because firstly, it looks nice and provides that smooth whole-body contour that's desirable in showy-type mice, secondly it provides more stability for them with better musculature/attachment as they use their tails when climbing/moving, but thirdly and perhaps more importantly than the other two reasons, these are domestic animals that will be handled. When you lift or hold a mouse by the tail, you should only ever be lifting or holding from the BASE of the tail, and if that base has a long lead out, then you have more surface area to hold, making it easier on the mouse and practically eliminating the risk of degloving.
You also want no kinks in the tail. This doe doesn't have a hard kink in her tail, but depending on how 'stiff' that curve is, it might be something you'd see reflected in an adult mouse, and MIGHT be cause for docked points in show. Or, it might be a growth issue that will even out as she grows and her tail muscles/tendons develop. It might also just be that she was flexing it during the photo. Trust your eyes over a photo on that front, but a lot of times taking a photo can help clear up differences in mice, since you can get control of the lighting and positioning better in a still frame.
So yeah! That's a look at mouse pink whisker beds and tail sets for quality, while breeding!