Not sure if pic was uploaded, but hopefully it did. I found this last night. Not sure what I did wrong. Any ideas? I have never seen this before, and the smell wasn't the best either. I think these are from a batch I did just the other day,but have no way of telling. I guess I will have to keep on eye on the rest of them.

After many years of canning tomatoes with nary a spoiled jar, I learned my lesson after ruining a huge pot of vegetable beef soup (3 pounds of choice beef roast) by adding two quarts of tomatoes at the end that were spoiled.  These tomatoes didn't look bad at all in the jar and I smelled nothing until I was finished pouring the tomatoes on top of the rest of the ingredients.

I always can at least 50 quarts of tomatoes, and always marked the lid with the year, but since that time, I not only put the actual date they were canned, I mark each jar by batch number so if they spoil I will know which other jars out of that batch might be spoiled.  That year I had seven potential spoiled jars mixed in with probably 75 good jars.  That was years ago and I have not had a spoiled jar again, but I still keep track by batch because there is always that possibility.

You are probably right about not cleaning the two jars well enough.  Even if I have washed jars very well for a canning earlier, but didn't use them, I do the wash job over again the next time I am ready to can.  I keep a teakettle of hot water simmering until I finish canning in case a jar or two needs sterilizing quickly. 

Additionally, I use the hot pack method and still I do the boiling water bath for 20 minutes per quart and 15 minutes for pints.  There is just too much work involved in producing tomatoes in the garden, the cost of supplies (jar lids are outrageous in price this year) and work putting them up to short-change the canning process.