I was holding, let me say, bad coins for a long time. I found out that it's not a good idea literally a few months ago. Now I think that if you getting some bad coins from somewhere - just sell it and forget about it.
Yeah, its hard to know if its a shitcoin in the first place since you are being feed with a good papers, the site looks so great, the whitepaper is so good and the team is very responsible but after months of holding, you will just realize that its not worth holding anymore. If you ended with a shitcoins better to let it go now than to be stressed while you are still holding.