For commodity resistors, sure. There are high-performance resistors though, and they are usually packaged with a manufacturers mark (e.g. some of Vishay's line).
Also, the resistance of the resistor is only part of what I care about when I specify the part. Temperature co-efficient and the technology behind the manufacture can matter quite a bit -- and those are harder to test.
Also, the resistance of the resistor is only part of what I care about when I specify the part. Temperature co-efficient and the technology behind the manufacture can matter quite a bit -- and those are harder to test.