"The conduct of man [...] changed into mere mechanism, where, as in a puppet show, everything would gesticulate well, but no life would be found in the figures" - Kant
This quote found in Kant's Critique of Practical Reason, even though it is describing the change which would take place if the Thing in-itself were to be discovered (as interpreted by Zizek in The Parallax View p. 22), could be applied to the strange phenomenon of bad acting.
Hyperreality, where the thing appears more real than real, because of some standards set by an outside representation of the thing in the past, meets its opposite with hyperunreality. I would say that hyperunreality can be applied perfectly to bad acting:
Acting out something which is unreal in a way which seems unreal by the standards of acting. A total and utter destruction of the suspension of reality. The believability of bad acting is a strange paradox, considering that a viewer of a fictitious television show, film or play is conscious of the fourth wall. When actors are overacting and emphasising and gesticulating more than they would in real life, the audience and the actors know something is wrong. The paradox lies in the fact that the actors are acting out something they don't feel, and the reason they are acting it out badly is the fact that they don't feel it. If they were to feel it, it would not be acting as much as reacting, so the good actor is one who can pretend they are feeling something without the emotion behind it?
Good acting, in my eyes, constitutes hyperreality. Especially in the mass media. Reactions to things are, again, paradoxically, stronger and more real than real life. When we are faced with the reactions of those around us, which are true and genuine reactions, we may feel underwhelmed by the fact that they are not as strong, luminous and emotive as those we have seen on the big screen. In fact, if you have never seen someone in real life act out a certain emotion or mindstate, hyperreality (or hyperunreality, depending on the circumstances) will come in to play. Standards of real life will be judged against the standards of the total and utter fantasy. As society relies more on media to 'feel things', the line between fantasy emotion and real emotion will either blur or turn into a gap, as we are no longer sure we are feeling the right things or when we judge our own feelings on the performances of those who are just acting - whether the acting is good or not.