To be safe there are three factors players view as important when choosing an online casinos. Casino popularity, casino bonuses and most important, casino security. Very few times it would be the online casino commiting the fraud. It could be between interaction with other peolpe through the site or the player himself commiting fraud agains the site.
The most common commited frauds by pleyers are the refusal to pay withdrawals or cheating the software with rigged payouts; also stealing sensitive player information and bonus abuse. A Rogue Casino is the name giving to a casino with multiple incidences of fraud. Blacklists of rogue casinos are kept by many gambling portals and player forums.