In DS9 the "Adversary" a changeling takes over the ship. I'm not exactly sure how he takes over the ship. But what I really don't understand is why Dr. Bashir doesn't scan the crew to see who isn't human. Odo has said many times he doesn't have a stomach and can't process food. Why didn't they just make everybody eat something.
Didn't they have other and better options then running around firing phasers at wide bursts all over the ship?
I'd like to clarify my question.
They did do a blood test that didn't work because the "Bashir" doing the hypospray blood test was the changeling, who manipulated the test. They discovered shortly after the test that "that" Bashir was a changeling.
Remember this was the Federation's first encounter with a changeling besides what happened on their homeworld when the crew of the defiant was hooked up to a machine. The members of the crew learned almost nothing about changelings during that time, being as their brains were hooked up to a simulation.
At this point in the series the Federation didn't know much about the changelings. Almost all of their knowledge was from Odo. Odo could not digest food, did not have a stomach, etc. Why not try that? They had no idea at this point what could or could not work.
My question was specifically about this episode, not later episodes, or using knowledge from later episodes in the series.