It doesn't do any good. I have sent alerts on these brands (and Purina) to everyone I know with pets. Most didn't even bother to respond. Until it happens to them, they don't care. Price and convenience wins the day, every time. The ones that have responded say the same things "it's a complaint board, naturally you are going to read complaints there". "They are just a few out of millions who feed these foods." "Their pets were probably already sick, or they got a random bad batch" "I have always fed this brand, my pets have always thrived (I beg to differ on the use of the term "thrived") I trust them completely"
"Just a few out of millions" really gets me. I bet if if was YOUR pet who was one of those "few out of millions" you'd be singing a different tune.
Not just for the brands listed in this thread, but the Purina, especially. Many people don't even realize what they are feeding IS Purina. When I urge them to look again, I get the same old song and dance, see above. It's very frustrating. I can't do any more.