How much does the appearance of the product vary?

Examples of variation: Color, Pattern, Shape, Texture, Surface finish, Material

How consistent are the product dimensions?

How many different defect types need to be detected?

How consistent is the appearance of each defect?

For example, a standard scratch that looks almost identical every time is very different from a surface anomaly that can appear in dozens of different ways.

How small are the defects you need to detect?

How difficult is it to distinguish a defect from normal product variation?

This captures the difference between finding an obvious defect and finding something that merely looks different from an acceptable product.

How consistent is the lighting at the inspection point?

How much do environmental conditions affect the inspection area?

How consistent is the background behind the product?

How consistently is the product positioned during inspection?

How predictable is product movement?

How many surfaces or viewing angles need to be inspected?

What is the production speed?

How frequently does the inspection requirement change?

What level of inspection coverage do you require?

How strict are the acceptable quality limits?

How important is distinguishing different defect categories?

How does the inspection result need to interact with your production line?

How much integration with existing equipment is required?