They use hype and high pressure, shill bidders, lies about buyers not coming through, etc.

Don’t Let the World Kick You In The Assets w/Cheri S. Hill

Real estate agents, banks, title companies, REI attorneys, CPAs, etc will all have less business, thus lower overall tax revenues from those supporting services.It's basically a shill promising freebies during the election cycle which happens all the time.  

At this point I am ready to walk away from the property, as it seems they may not truly be serious about selling, and are just shilling for an overpriced offer.

Most investors will run shills, and I had an HUD guy tell me last year that they got 40 bids from the same IP address, and they started watching for shills.Joe Gore

Robert some lenders that hold the deed that send their proprieties to the auction will put shills in to bid up the price.Joe Gore

People come on here shilling their crap, and it always gets immediately taken down because the moderators are awesome.

I really don't think he'd play a shill at this stage of his life.

I'll say, considering that BiggerPockets was an unknown quantity to me before this, shilling out $250 bucks (I was late to register but thanks to Marty Boardman's video clips I found out about it in time) seemed a bit on the risky side.

There is a lot of shill bidding on auction.com.