Trust is something that takes a long time to get in this world. It can take months to gain trust from players, but it can also be completely gone within days. On the forum it is useful for people to give their opinion about the reputation of a site, it is very useful. Being active on the forum and paying players is the best way to keep your reputation high.
A site that has a lot of promotions will make the community more engaged with the site, and with good support, that is a combination for a successful gambling site. Our community here loves a legit gambling site, and once a gambling site already gets the gambler's support, expect that money will be flowing, however, good communication has to be maintained and reputation can easily be ruined as well.
I'm seen some gambling sites here that started well but ended up getting bad reputation from the community, resulting the representative to leave the forum which they failed to realize it's a big market forum.
fast resolution of any issues, whether big or small is very much appreciated by the players. so the owners should always see to it that there is no existing issues or allegations on their site. because if the players will see that they are treating everyone as equal and they can always get answer from their support, they won't hesitate depositing more money as they know they are well taken care of. so for me, one thing to look at is the visibility and resolution of issues. but of course the bookie can always hold regular contests or bonuses to sustain their players' interest.