I think if you don't give someone a machine you should be pretty forgiving about exact syntax.
Someone who can put together a statement that's broadly right with small errors normally means someone who is rusty (or nervous) but knows their stuff rather than someone who is guessing and a couple of follow up questions will usually confirm that.
General rule for me: don't ask anything that a decent IDE or 10 seconds with a manual / help file / Google would have prevented (unless you've given them a decent ID or similar in which case it's fair game).
Someone who can put together a statement that's broadly right with small errors normally means someone who is rusty (or nervous) but knows their stuff rather than someone who is guessing and a couple of follow up questions will usually confirm that.
General rule for me: don't ask anything that a decent IDE or 10 seconds with a manual / help file / Google would have prevented (unless you've given them a decent ID or similar in which case it's fair game).