There are good ones and bad ones. Like
@ChpBstrd said, sometimes high yields are phony and represent significant return of capital and the NAV falls slowly but surely over time. You want ones with a long track record where you can see a 10 year history of distributions that is stable or rising, that is not heavily relying on ROC distributions, has stable or growing NAV, and (especially) to buy at a discount to NAV.
I currently like BIT and CHI in the space but I got in on 1APR2020 when the discount was wide and the NAV was showing a temporarily COVID-19 hiccup (up 28 and 42% respectively already). In preferred shares oriented CEFs, JPS usually offers a good value. Super high yield CEFs like JQC and OXLC are toxic. I have also had good long term results (since 2014) with tax exempt bond funds IQI and NEA - those are both within a few percent of purchase price but reliably pay out a fed tax exempt monthly distribution over 4.5% with sleep well at night low volatility.
Understand what you are buying. Most CEFs should be thought of as part of your bond or hybrid securities allocation. They are not "set the world on fire" investments. And as noted, they fees are very high compared to indexing. You are paying for professional advice in low liquidity areas of the market and usually for some interest on modest leverage.
@crking
