This is related to my other question. There, I was asking what exchange traded funds I should consider for inclusion in my retirement portfolio. That got me thinking: What kinds of exchange-traded funds (ETFs) should specifically be avoided?
There are thousands of ETFs and index funds out there now, and I'm guessing some of them are poor products just trying to cash in on the popularity of ETF-based investing.
So, without necessarily getting specific about particular products, what kinds of ETFs tend to be poor choices for a retirement portfolio?
For instance, should levered or inverse ETFs be used in a buy-and-hold retirement portfolio? Why or why not? Are there specific "sector" funds that should be avoided?