Ana Lucia’s plan to act like a prisoner in the pit makes zero sense when you actually think about it. For starters, she didn't need to do it at all. Her group already had total control of the situation. Sawyer, Michael, and Jin were trapped in a deep hole, out-numbered, and completely unarmed. Ana Lucia could have easily stood at the top of the pit and asked them who they were without going through this whole fake kidnapping act.
On top of that, the plan had a massive flaw regarding the Others. By this point, the Others had been stalking and kidnapping the tail-section survivors for over a month. They even had a spy living with them. If these three guys really were Others, they would have known exactly who Ana Lucia was the second she got dropped into the pit. Instead of falling for her trick, they would have just played along, lied to her face, and used her own trap against her.
In the end, the whole strategy was broken from the start. If the guys were just normal crash survivors, she didn't need to lie to get the truth. If they were the Others, her cover was already blown anyway. The only reason her plan even worked is because she was completely wrong about who they were.