First gambling ads is everywhere, you can't expect a website discuss about environment will not have gambling ads, no, it's happen. Second when you go to stores or marketplaces, there's might be a gambling flyer in street. Third, your friend might be a gambler.
Advertising for the promotion of gambling sites is the most widespread on several social media such as Facebook, Twitter, and YouTube, while for now it is not only on social media, but at every sporting event that takes place, even gambling sites sponsor several teams, there are events. sports to get their names listed and broadcast globally.
If it is in a living environment such as a market shop or a street it depends on which country they live in because some countries prohibit gambling so it is impossible if there is blatant advertising on the street, friend.
What is sure to quickly get attention in doing advertising is at sporting events and on several social media and until now there seems to be no limit regarding advertising of gambling sites.