Plant's often do not look their best during their dormant stage this is quite natural. Almost all plant's die back or even right down to soil surface in the fall and winter. The dead leave's often serve to protect the underground root system from cold and frost. They rot away or become mouldy in wet winter month's this is a natural function of the leave's plant may appear to be sad looking.
Checking plant quality turn the pot upside down then loosen the rootball by tapping the bottom of the pot several time's carefully remove the pot from the plant. The quality of the rootball determine's how healthy the plant is. The root's should show clearly round the whole root system. If you compare several varieties will see that not all plant's have same root's this is because different species have many root characteristics. The difference's between plant's are not limited to top growth stem's, leave's, flower's, and growing habit.
What count's is how well the plant has grown in a larger pot over a period of time this is automatically a better plant with a good root system which is larger than would have been possible in a small pot. Transplanted plant's during the growing and flowering stage are more vulnerable to failure. They require much more care and often deteriorate after planting. Plant as soon as possible firm the soil well water immediately and repeat occasionally as required to keep rootball moist.
If you order shrubs from a specialist nursery you depend on them to send specimens of proper age and development for planting. When you go to the garden center you make your choice from the container grown plants on display.
Such shrubs should have been in their containers long enough to have become established and not recently planted in them. On the other hand they should not have been in the containers for so long that they are root bound and possibly starved.
Try to pick shrubs that have a good shape with shoots radiating evenly from the center. Lift one or two out from the others to inspect them. Reject any whose growth is lop sided. Also beware of any that show signs of having been pruned hard.
Be extra critical where only two or three plants of one type remain they could be the runts of the litter rejected by everyone else.
Choose plants with normal healthy looking foliage. Avoid any that show signs of being stunted, have undersized leaves or show unusual yellowing, bronzing or scorching. Such symptoms could indicate past starvation. Check too for signs of pests or diseases, or cankered areas on the wood.