A key distinction is the "grows true", which I interpret as "breed true", i.e., the seeds are non-hybridized. For a bit more detail, see https://en.wikipedia.org/wiki/Heirloom_tomato#Seed_collectin...

Interesting. As for OP's experience above, a more important distinction is whether the "heirloom" tomatoes sold in grocery store are actually heirloom, according to this definition. I know that in Canada they aren't always.

My point is that you can lead a horse to a stream but if its a drought and the stream's dried up, they couldn't drink from it if they tried. doesn't matter if the horse is genetically more of a pony, stallion, mule, zebra or unicorn. nope, if there's no water, the horse can't drink.

These tomatoes were not only spongy (which I'd expect from shipped tomatoes), they just had no taste.

http://njfarmfresh.rutgers.edu/documents/tomatosalt2009.pdf

I did a little research and found that there are a few more possibilities. Maybe the tomatoes were grown hydroponically. Maybe it was very rainy or they over-watered before harvesting. (https://www.npr.org/sections/thesalt/2012/06/01/154072388/ho...)

I assumed "depleted soil" because that's a rampant problem, but it could be other stuff too.