It isn't so much the ice machine. It's the pop. The lines are plastic and require mandatory flushing out and super cleaning regularly otherwise the sugar syrups leave traces in the lines that breed bacteria because bacteria loves sugar. If the lines aren't maintained 100% [ which they rarely are because it's tedious ] , those buggy bits have a chance to build up and transfer to the soda as it gets pushed through the lines. Most people might not notice anything, some will blame the food if there are problems. It all depends on your particular health at the moment you took a sip.