What do old farts have to do with amps you ask?
Old bass players just love their tube amps.
The warm blu glow of a hot tube is a normal thing. When I see that, impurities come to mind. A hot flash isn't normal. Old tubes can develop problems if there is too much voltage placed between the anode and cathode. The current flows through the tube. This happens because opposites attract. Too much flow and the it can get red hot. A hot a bias can make this happen.
Now if the tubes are hot and things are amped up the speaker gets going. When it comes to air, speakers suck and then they blow. They do it over and over again. If they don't do it in a musical way, people say their speakers suck. If a speaker gets overextended, it can blow. Old speakers fart when they can't take what is fed to them.
Old farts can't always perform like their amp can. This can make them grumpy.
quod erat demonstrandum