No, they certainly do not work in my opinion.
Was working once, doing a sleep in at a tenants flat. D had been having trouble with a couple of mice and purchased three of those plug things to try and get rid of them and she told me when I arrived she had still seen the mice.
That night, I went into the kitchen to get a coffee, switched the light on and a mouse was actually sat on top of the plug thing....enough said?
The next day, the council came and sorted it!