Can I request all twelve at once?

You can ask, but a warehouse will usually batch them. Prioritise the decisive tier and add the rest only if something looks off.

What if the agent refuses a measurement?

Some do, some charge. If a measurement is refused and the item is expensive, that refusal is itself information about how the return would go.

The first four items do. The diagnostic tier changes by category — midsole stitching matters for shoes, GSM for fleece, hardware finish for bags.

Label photoThe size and composition tag, legible. This is the only document that survives the parcel.
Flat measurementChest or waist measured flat, with a tape in frame. Not a number typed into a message.
Weight on scaleA number on a scale, not an estimate. This is what your freight is billed on.
Both shoes, side by sideToe height, heel counter, midsole line. One shoe hides everything.
Sole and outsole patternCheap soles are thin and flat. A photo of the tread tells you more than a photo of the upper.
Inside lining and insoleStitching inside is where a replica falls apart first, and it is the easiest thing to photograph.
Hardware close-upZips, buckles, snaps. Engraving should be crisp, not stamped and soft.
Print and logo close-upEdges of a print are either sharp or fuzzy. There is no middle ground at this price.
Seams and stitchingEven spacing, no puckering, no loose thread ends. Pick one seam and judge it.
Colour under neutral lightWarehouse lighting is yellow. Ask for a photo near a window if the colour matters.
Packaging as receivedPoly bag, box, tissue. This is what the seller actually shipped.
Any damageScuffs, glue residue, a bent corner. Better to know now than after the parcel crosses a border.

Order

The first four decide whether you ship at all.

Tiered checklist
Tier	Items	What they decide
Decisive	Label, flat measurement, weight, both shoes	Whether the item is the size, cut and weight you ordered
Diagnostic	Sole, lining, hardware, print	Whether the materials are what the listing promised
Confirmatory	Seams, colour, packaging, damage	Whether anything happened between the warehouse and the photo

Thresholds

Numbers, so the argument is about the measurement and not about taste.

Decision thresholds
Measurement	Acceptable	Ask for a return
Chest width vs chart	Within 2 cm	More than 4 cm
Garment weight vs listing	Within 10%	More than 20% lighter
Shoe length vs size chart	Within 5 mm	More than 1 cm
Toe height, left vs right	Not visibly different	Any visible difference in a side-by-side photo
Sole thickness	Within 2 mm	More than 4 mm difference between pairs