I have the same thought as janis g, the glass must be etched by crud. When something green, brown or black such a mold is growing in unwanted places, I'd go with the big guns, liquid bleach and I even clean my drains regularly with a mixture of soda and bleach. Most of the time I go with the "green" cleaning products, but there are times when I need more power.

I try to remember to add vinegar each time. I'm amazed the difference if I forget. The jars will come out with the white haze on them. Fortunately, since it hasn't been many times, the white film wipes off. We have special a salt addititive to put in the dishwasher here to help keep the glasses from getting etched. It was a hassle adding that stuff to the resevoir so now I just take the easy route and buy the tabs with the salt built in. Over here, Calgon sells tabs for the clothes washer also. You add it with the regular detergent. I use those also. The regular powder didn't dissolve very well in my pesky european washer.

Actually, they are useful for so much more than protecting against scratches (which I don't care about anyway): Water doesn't backup into the colander when draining pasta When I rinse down the sink, items in the sink no longer block the drain or block the "path" to the drain so I don't have to "chase" specks of food, etc. around the sink! There is less scratching of the bottom of the sink (this is minor to me since I don't mind the scratches) When I dump something in the sink, whatever I've dumped doesn't wash all over everything sitting in the sink....whatever is dumped goes straight down the drain I can rinse and drain dishes on the grid and still run water in the sink w/o running it all over the items again Things lay flat on the grid (no slope like in the bottom of a sink bowl and items in my sink no longer slip down the slope and cover/block the drain) If I'm handwashing dishes, I can use the grid tines to hold things up, especially plates & bowls (similar to a dish drainer) and dishes air dry faster b/c air circulates all around them If your sink is too deep for you on a daily basis, the grid will raise the bottom of the sink an inch or so Less need to clean/wipe the bowl b/c things aren't as likely to "stick" The stainless steel ones in my cleanup sink also act as a trivet for hot things (when the sink is clear, of course!) -- I needed a large "trivet" once and used one of the grids from the sink, it worked great!

rob333, this old fogey has discovered that no matter how many myths are busted, there's always more to come. I came back to add that I just tried something that truly surprised me. Was at my neighbor's and he was talking about the terlit buildup lately and it jogged my memory about a cleaner I saw endorsed by several people. Zep Acidic Toilet Bowl Cleaner. I had bought some and never got around to trying it so I went home and got it and we gave it a shot. Squirted it on, let it sit 5-10 min and gave it a quick brushing and I was really shocked. Half of the crusty buildup came off right away. Wasn't perfectly clean but I wonder if a sandblaster would still have crust on there. I left the bottle for him to give it another treatment in a day or two and see how it works. I don't remember where I read about it so I can't give credit but I'll be buying it from now on. I should also add that I did NOT scrub it either, just a brushing with a well-worn scratchbright pad type toilet bowl "brush". Didn't try it with the pumice stone but I'd venture a guess that pumice would help it too.