It may depend on your local rules, but here it's certainly better to put a recyclable thing in the bin than a non-recyclable thing in the recycling. That's because our council don't have any sorting facilities, so if they deem the recycling to be 'contaminated', they'll send the whole load to the incinerator - whereas if you put it in the normal rubbish, it's just that one item that's wasted.

This might vary in areas with a more enlightened local authority.

It may depend on your local rules, but here it's certainly better to put a recyclable thing in the bin than a non-recyclable thing in the recycling. That is, if your council doesn't have any sorting facilities: if they deem the recycling to be 'contaminated', they'll send the whole load to the incinerator - whereas if you put it in the normal rubbish, it's just that one item that's wasted.

This will vary in areas where the recycable materials are sorted: there the 'unwanted' items are picked out (often by humans) and discarded. You then assume that they will know what you are unsure about.