No, but I did spend $15.00 (plus shipping) for an at-home "test kit"! According to those several results, we have no nitrites/nitrates or anything else bad, our softener is doing its job, and we have a Ph of around 8.5 ... but I have no idea what that means.
Yes, I have at least heard about the iron-related bacteria. When we first got this place a couple of years ago, it had been empty for a year and the one filter we had at that time was quite black. Since then, however, the only black I have seen is the hard scale inside the tank connector, and we have only had that "twang" a couple of times, once badly, yet without any "black" either on the filters or past them.
At the moment, I am planning to remove the anode from the water heater to see what effect that might have in relation to our slight come-and-go or varying sulfur odor that is occasionally more in the hot water than in the cold.