Players often find ads for a no deposit bonus and when they download the casino they find out the offer isn’t available. What has been happening is the offers expire and the casino groups do not tell the advertiser so it was never intentional on the part of the website that listed the bonus. It is lack of communication on the part of the marketing team for the online casinos. If a player does find this has happened to them the odds are the casino will probably still honor the offer but most people would just go elsewhere to get a bonus. You can hardly blame them as they feel tricked and then no longer trust the site they found the bonus from. Overall it is not a good situation for all.
If you have come across one of these offers and took the time to download the casino, went through the sign up process and found you could not get the no deposit bonus. Complain to them and show they the ad you found. Especially if the ad goes to a landing page that clearly displays the bonus. As the site owner will not be happy to know that the casino is not honoring a bonus so no worries about them, they would rather you complain.