Good old Hat Lek border crossing with overly corrupt Cambodian officials. I went there last year with my girlfriend who is a from a middle eastern country. It is clear on the Cambodian Gov't website that she was eligible for entry to Cambodia with a visa on entry. We cleared Thai immigration with no problems. We were then approached by some tout at the Cambodia immigration post who asked what we planned. I told him that we wished to get a Visa on entry and visit the casino and a restaurant. He told us that the visa fee would be 3000 baht each plus 300 baht each to leave the same day. I pointed out to him that the actual cost was about 1500 baht each for the visas and told him that I would deal with the official at the office. He said suit yourself. I went to the window and they demanded 3000 each. I asked to speak to the boss and was shown into a room where the boss also demanded 3000 baht. I tried telling him that as per the official Cambodian gov't website the price was 1500 baht. He wasn't having any of it. I was trapped outside Thailand with no way to return without paying the 3000 extortion fee. I ended up paying. Never going there again. I did notice that other travelers had E-Visas and had no issues or extortion demands.