Hi @awfunn, thanks for inviting me to share my experience.
About four months ago, I started to experiment with vote selling through minnowbooster (by buildteam). I found it useful to automatically upvote posts on steem whenever I am not active.
After about a month or so on minnowbooster, I discontinued the service and opted for vote selling on smartsteem. Shortly after that, I configured smartsteem setting to blacklist a particular account from buying my upvotes, as this account was receiving too many of my votes. This account is an aggressive buyer of votes. I didn't like the fact that most of my upvotes were going to this particular account. In addition I didn't quite like his genre.
After the blacklisting, someone was still upvoting posts authored by this blacklisted account. This is when I started investigating and found that besides the blacklisted accounts, my votes were being used to upvote other accounts too. Because I had a blacklisted an account I could detect it without much investigation, just my merely watching the notification on my steemify account. However for the other accounts I had to do a comparison of the upvotes in the smartsteem records and the actual upvotes in the blockchain, using either steemify notifications or the steemworld.com.
As a first step I sent an enquiry to smartsteem and requested for clarification. Smartsteem replied saying that it is not one of their staff and since I had then authorized about 25 dApps, the vote stealing could be from any one those 25 dApps.
I then changed my master password (and consequently all the 4 other sets of keys) and subsequently used less than 10 dApps using my new keys. For about 2 or 3 weeks after that everything was okay and then the vote stealing started again. This time I had to change the the master password for the second time again.
Since then I have not been very vigilant in looking for vote stealing because whilst the vote selling on smartsteem is active it is quite difficult and time consuming to continually and regularly do a comparison of the actual upvotes against the upvotes in smartsteem records (and my own manual upvoting). It would be easier if I am not selling votes and probably that is what I will do next to make the process easier. Notwithstanding, the random checkings I conducted now and then, did not disclose any discrepancy except for the false positive that triggered this post.
Hi @devann, this topic is interesting, my team and I usually do not use any system of selling votes or buying them, we have not registered on any web of that type, so we have not had any problem with that , but I hope that you solve your problem and that it does not happen again, @crypto.piotr is a great friend who shares interesting things with us, but this one astonished us, nevertheless when reading the comments we reached the conclusion that the best in Steemit.com is not to register in any third-party application that did not participate directly with Steemit.com, we have made several posts and we will do one on topics such as websites outside the core of Steemit.com
Thank you for sharing your story and for reading.