Bad lamps are almost always a result of bad handling. During manufaturer, all lamps are tested automatically, and an automated sensor mechanism kicks bad lamps out of the line.
Quality comes into play when a lamp gets kicked around a little. A better made lamp should be able to take a little abuse, and conversely, a cheaply made lamp will fail - usually at a weld junction. I find that the lamps that are better packaged to handle shock and vibration during handling tend to deliver a much lower failure ratio.
Although you can't do anything about the shipping and receiving guys at your supplier, a little bit of care and thought from the end user should give a few less failures.
Good luck in the future!
