So so true.......that's why I always use a ph meter, this year I jarred and processed some various salsa's, water bathed some and pressure canned the relish types,
Recently I brought up a couple of cases to my kids at school, prior to doing so I grabbed a few jars out for myself, "Pineapple/Mango" .."Salsa Verde" "Black Bean Corn Relish" and a few others, not surprising but the ph on all jars were about 3.6.
I knew the salsa's would be fine, I was just curious on the tomato based relish types that were pressure canned, those ended up being 3.7, that's basiclly where I capped them at.
As long as the lids are down, and there under a year old I don't see the need to recheck the ph , but it was a boost of confidence to see it with my own "eye-balls" the first time...
Greg