Most people evaluate a T-shirt by look and by price, in that order. Neither tells you much about how the garment is actually going to perform. Here's what a closer look — thirty seconds, no special equipment — actually reveals.
Start with the seams. Turn the garment inside out and look at the shoulder seam specifically. A reinforced or taped shoulder seam sits flat and doesn't pucker when you stretch the fabric slightly — that's a sign the maker cared about a stress point that fails early on cheaper garments. A seam that bunches or pulls under light tension is a preview of what will happen after a few months of actual wear.
Next, the collar. Press it between your fingers. A well-constructed collar has some structure to it — it holds its shape and springs back rather than folding flat and staying that way. Collars are usually the first thing to visibly wear out on a T-shirt, so a collar that already feels floppy on the rack is not going to improve with washing.
Then, hold the fabric up to light. This is the single fastest test for weave density and GSM. A tightly woven, higher-GSM fabric will let very little light through evenly. A thin or loosely woven fabric shows visible gaps or an uneven pattern of light — an early sign it will stretch out of shape and lose structure faster than a denser weave.
Finally, check the print or embellishment, if there is one. Run a fingernail lightly across it. Screen printing that sits heavily on top of the fabric, as a distinct raised layer, tends to crack and peel faster than discharge printing, which dyes into the fibre itself rather than sitting on top of it — you'll feel almost no texture difference between the print and the fabric around it.
None of this requires expertise. It requires thirty seconds and a willingness to actually handle the garment before it becomes a chore to return.