Britt noted that lots of funds file but never launch. Lots of funds launch and fail, with taxable consequences. There have already been 26 ETF closures this year, according to ETF.com.
Any fund that has raised less than $25 million after at least three months on the market has a liquidation risk that is high, Mishra said.
The classic example fund-watchers point to is HealthShares, which launched more than a dozen funds targeting medical and drug trends in the late 2000s but went under swiftly.
"Go back and look at all the hype," Gordon said. "It ended up with all things going under because there was no liquidity."
Mishra said there is a better chance that a bigger fund company, like an iShares, sticks with a dog for longer because the economics of that fund won't be important to its overall financial performance.
Gordon said that for investors who think they can properly use narrow investments, "Wait for a big fund company's version of the esoteric fund. ... The very biggest of families will let things that should have died exist for years."
— By Joe D'Allegro, special to CNBC.com