In Star Trek: TNG, Data is Fully Functional (youtube link.)
This idea is also explored in Issac Asimov's Robots series.
For these questions assume that the robots must obey the 3 laws of robotics.
- Would they do whatever humans wanted, essentially being sex slaves?
- Would they actively go out and seek partners?
- Would they replace live actors in porn? (after all they don't get tire, sore, or need a break from the [ahem] activity)
- If told to enjoy themselves for the activity, would they be able to?