I could never take a part in a scene involving smoking – unless actors have a way round this such as smoking rolled cabbage leaf. (But I could take part in a scene involving drinking. I once had a whisky bottle stolen from the changing room: I would love to have seen the thief’s face when he took his first swig and discovered it was cold tea!)
I could never take a part involving driving since I don’t drive.
I couldn’t take part in ‘intimate’ scenes with anyone, however glamorous or outwardly attractive that person might be. We have to draw the line somewhere, right?
I would never remember the lines. I know this because I’ve tried it and failed, though blank verse or rhyming couplets would improve my chances. I explained this failing to a director who nevertheless recruited me to play a part in an advert. The location was a pub. I ended up writing my lines on beer mats. Despite completing the ordeal, the ad was never used.
Last but not least, I don’t have the talent for it.