@Steve B. Hi Steve, nice to hear from a fellow engineer. You are correct that there is an inverse relationship between cash flow and appreciation, but how tightly correlated those two variables are depends on the market in question.
For instance, in the commercial mutli-family market those two variables are strongly correlated because the primary buyers of multi-family are buying as an investment. However, in the single family residential market these two variables are only loosely correlated. Other forces become the dominating market factor.
Real estate values are inversely proportional to the debt service. When mortgage payments go up, values go down. So if the area has a high tax rate, when values go up, taxes go up, mortgage payments go up, and values go down. There is a counter-balancing effect with high taxes. Similarly, if the area has high insurance rates, like a flood zone, there is a counter-balancing effect. As values increase, insurance costs go up, mortgage payments go up, and values go down. These two things tend to cause flat markets (very little to no appreciation).
Rents in these areas tend to continue increasing over time but since values are kept down, cashflow increases. Some of the best markets for cashflow have very flat RE values. I may buy some property in these areas just for cashflow, but my main focus right now is appreciation (until I hit my goal of 3 million equity) so I will mostly avoid these areas. Other appreciation killers include high crime and declining population.
Interest rates are also inversely proportional to RE values, but interest rates tend to affect the market as a whole.