How true that is! Things have gotten better in the last few years, but back when DIMMS were new and the LX chipset was all the rage I went through entire cases of RAM from different manufacturers. Sometimes it was completely defective. Sometimes it just wouldn't get along with a certain board even though it worked in everything else. Sometimes it was good one day and not the next.
The only good thing about those times is that the survivors all troubleshoot by saying it could be anything, nothing, or EVERYTHING!