That's an interesting thing for you 51. Usually its the other way around. Properly soldered joints are the gold standard of low resistance connections. It looks like you are experiencing a rash of bad craftsmanship! It is probably going to become rare to find anyone who really knows how to properly solder anymore. Or for that matter a manufacturer who can do it as fast as they need to do it now a days. The modern push in styles and solder-less connections are definitely faster. My first quarter in electronics way back was spent learning how to prep the soldering iron, solder joints and apply the heat correctly. I don't think they teach that stuff anymore!