Honestly, theres a right way to do it as I notice some members have multiple accounts and they will deny this as some people do not do well at this. The big give away is their IP address and even that they will deny at times.
I have used dummy accounts before using a proxy or VPN server to make them seem real to staff seeing as staff can see IP. You can also generate a false email account to register with the account (making new email can be a waste of time) no problem in a matter of seconds if you know where to look on the search engines so you can make more and than juggle the accounts.
Its hard to tell the difference if you're doing that and...using other sources for posting content. Other than that, people think its a new member posting and won't point any fingers unless the IP is also tied to your account. Other than that, you're free to post new content all over your forum making it as though that member is real.
I think using false accounts is a great way to get your forum up and running. If it's brand new you really don't have much content. Plus, you really can't get anywhere with no content. So by using the false accounts they kinda give you that boost in the right direction you need to kick start your forum off. I've used them a few times in the past and they really help a lot.
I think I may have done this before in the distant past, but not recently. Generally, I prefer to do exchanges. They result in better content, yet you have to do the same amount of posts.
They could be used to test new features and such, but otherwise should not be used to make your forum look a little bit more active. It will give a bad impression and other members would be let down if they were to find out.
I have dummy accounts, and they are usually used to test permissions so that I can see if I added something correctly. When it comes to posting, I don't usually use dummy accounts to generate content, since I could be using my regular account to do so.
Personally, I've only ever used a dummy account while testing different groups/ permissions etc.
Never would I use dummy accounts to post and make it look like the forum is active or what not. I have seen blog sites do that though, fake Facebook profiles posting in the comments etc.
Yes, I have actually. It's fun making your own dummy account and giving them a personality and characteristics all unique to them. I've had fun debates and talks with my own self and it actually creates more content and posts, and makes it look like someone is active. I've even warned a few of my dummy accounts for breaking the rules.
I've heard stories of administrators and moderators getting away with pulling that stunt. No one ever felt compelled to call a suspected "member" out. If you can pull it off quietly, then it shouldn't hurt to at least keep forums a bit more active. What inactive forums need are more discussions, and not mere replies.
Otherwise, it's best not to attempt to deceive your community. It's a dishonest tactic.