The first thing I check is the bottom, where the glaze meets the foot of the dish. A cheap serving dish will have a rough, unglazed ring that scratches the table the second you set it down, and after a winter of sliding dishes across the farmhouse table at breakfast, you learn to feel for that before you even look at the pattern. A good one has a smooth, finished base, some weight to it, and sits flat without rocking when it's full of potatoes and you're trying to serve twelve people at once.
Where these go wrong is on a table that's already busy. A heavily patterned dish on a table with patterned linens and patterned plates just fights for attention, and nobody wants to look at a roast that's competing with three different florals. I keep mine plain, mostly white or cream with maybe one deep color for the big holiday pieces, because the food should be the thing your eye lands on, not the dish underneath it. The honest limit is that a serving dish is only as good as how often you actually haul it out. I own a gravy boat so elegant it's basically furniture, and it sits in the cabinet eleven months a year because it only fits one job and does it beautifully and nothing else. If you're buying for a small kitchen or a rented place with no storage to spare, skip the single purpose pieces and go for dishes that can hold a salad on Tuesday and cranberry sauce in November. The cheap version of a good all purpose dish chips at the rim within a season, usually right where it gets stacked, and then you're serving stuffing out of something with a jagged edge that catches a thumb every single time. A good one survives being stacked, washed by hand, and passed down a table of hungry guests without a mark to show for it.
These earn their keep most in homes where people actually gather around a table rather than eat standing at a counter, and especially in the colder months, when a big dish of something hot goes from the oven to the table and needs to hold heat and hold its shape while everyone reaches across for seconds. A guest wrote in my book once that the dish of scalloped potatoes looked like it belonged on the table forever, and that's really the whole test. Summer entertaining can get away with lighter, cheaper pieces because nothing's sitting out too long, but a winter table full of root vegetables and gravy needs something sturdy underneath it.
These belong in a house where big family meals are a regular thing, not an occasional event.