these days ~ I'm not that surprised!
There are made from Mechanically Recovered Meat (MRM), it's a sort of slurry that is blasted off the bones with a water jet and then partially dried. Not too dry of course, that water adds extra weight and therefor value, but enough to stop you noticing it.
Proper sausages are a different matter.
Good Health is very much a matter of balancing what you eat and it's content with, how much you do.