Well, now I've seen it with my own eyes. I have been using Coinpot for some time, and have made several successful withdrawals.

I'd seen all the warnings, and didn't disbelieve them, but had never been burnt myself... until now.

I made a withdrawal request on the 16th (2 days ago) for some Litecoin. I only selected a portion of the Litecoin I had as it was the first time I'd withdrawn Litecoin from them and wanted to be sure it would go smoothly.

Well on the 17th, the site went down for maintenance without warning, and when it came back up, the withdrawal request had vanished from my Litecoin history, but I hadn't received them. The coins were still missing from my Coinpot balance, but to top it off, they had taken the coins twice! It was like I never had the coins when looking at my history, even the graph that shows historical balance showed that I never had them!

It wasn't a major amount in financial terms, but my trust is now hanging in the balance. If they do that to a large number of customers each time they have maintenance, it will mount up, and most people probably wont notice. Trust is paramount with these type of sites, and if they're skimming then they can do one!

I've emailed support, I'll see if they bother replying and report back. I guess it's possible that it was unintentional, but I somehow doubt it. In the meantime I've requested the withdrawal of the rest of my Coipot balance.