Healthy plants, lots of tomatoes but they all get the bad spot that rots the whole tomato. What is going on ??

That could be many different things. Tomatoes don't get the disease that roses get called "Black Spot" but there are many different things that can cause a 'black spot' on a tomato - some of them serious, many of then nothing serious at all.

Can you provide a picture of what you are talking about? More details and description?

There are lots of photo tomato problems solving websites with pics to help you identify exactly what you might be seeing. I linked one of them below.

As for giving away extra plants, I do it and so do many others here. Same goes for giving away tomatoes.

Dave

Here is a link that might be useful: TAMU Tomato Problem Solver

Betsy, I think you need to distinguish between black spots on the foliage of which the most common are Bacterial Spot and Bacterial Speck, as opposed to BER ( blossom end rot), which is almost always found at the bottom of the fruits, the blossom end.

BER usually doesn't cause the whole fruit to rot, just the blossom end but there's also a condition called internal BER where there's no indication of anything wrong with a fruit until you cut it open and it's all black inside. But internal BER is the rare form of BER.

BER and the common foliage diseases have been around forever and ever, so I'm not sure why you suggest that either BER or the bacterial foliage diseases seem somewhat new to you ( "black spots")and by implication, perhaps some of your friends.

The TAMU Problem Solver that Dave linked to is a good one and I'll link to another one I think is good, which is the Cornell one, below.

Carolyn

Here is a link that might be useful: Cornell Problem Solver