Maybe just go back to the level and then go the pause menu, to see if you put a boo or not. (since once you like or dislike a level, you can't go back)
Also, did you watch the video I show you before? Because the thing is, I don't know what you consider a good or bad idea, so the advice I can give, is that you should try or watch others peoples level, see what you like in those levels, then use those ideas for your levels, tho, don't put too many ideas one level, just take one element like thomps or claw and combine them with other elements to see what they can offer.