There are major differences between the type of mystery auctions that eBay allows and the ones that will be canceled.  Regardless of whether or not you put a disclaimer in the description saying:

As per eBay and PayPal rules, this is not a lottery, raffle, giveaway, charity, gambling, etc. It is not illegal and complies with eBay's and PayPal's rules. You are buying an  Envelope and only an Envelope. Anything contained inside of the Virtual Envelope is simply a gift from me to you.

If your auction has ANY of the following, it is ILLEGAL:

If you, as a seller, can list an auction, have it won by someone, and then NOT be obligated to send anything other than some cash through paypal, THEN IT IS AN ILLEGAL RAFFLE.

I have been watching many of the illegal mystery auctions going on.  Almost all of them involve keyword spamming and feedback extortion.  Most of them have a title and photo of a high-dollar item such as the latest video game consoles or coolest electronic devices.  But the seller doesn't actually have it to sell.  Instead they sell the chance to win it from them.  But since they are the ones rolling the virtual dice, the auction winner won't ever win the prize.  Only a fraction of the winning bid.  If you check the feedback of some of the repeat mystery auctioneers, you won't find one that actually has a winner of the prize.  If they do, then it is the same ebayer with a different account.

So here is what I am doing!   I wrote a macro (a computer code that executes simple tasks very fast and automatically) that selects all the mystery auctions that I think are illegal and copies the item numbers into ebay's reporting system. 

I can report hundreds of auctions in only a few minutes. 

So far, I have shutdown almost a thousand illegal auctions in the last few weeks.  Several of my target sellers have been suspended.  I routinely watch them to see if they return to their illegal ways.

What I am doing is a service to help clean up ebay.  And if these sellers don't shape up, they will have their accounts canceled.

Don't worry if your running a legal auction because if I report it and ebay doesn't find it to be illegal, it won't be canceled.  Simple!

I am not the one making the final decision about the legality of your auctions.  But I will report any mystery auction that seems to me as shady.