Tons of people use sex toys, so sentient robots (or sex toys) seems like an obvious yes. Aliens though depend a ton on how close to human they are, and if they are "sexy" in some way. If I found an alien sexy, and it wanted to have sex, I'd be down for it (probably make sure they don't eat you afterwards first though).
Nothing wrong with sex with anything that enjoys it as well in my opinion. Probably should make sure they can't impregnate you too though...cause even if your a guy (like me), aliens might have different methods of procreation. Nothing like getting it on with an hot sexy alien bee like creature, only to find it has laid eggs in you and your gonna have babee's eventually.
Nothing wrong with sex with anything that enjoys it as well in my opinion. Probably should make sure they can't impregnate you too though...cause even if your a guy (like me), aliens might have different methods of procreation. Nothing like getting it on with an hot sexy alien bee like creature, only to find it has laid eggs in you and your gonna have babee's eventually.