Using the carb cleaner around a running engine can have two unpleasant results. First it can migrate in around the air cleaner seals and give a false result causing non required repairs so I made a long snorkle to set on top of the intake housing moving the fresh air source high above the engine. I actually started using a water spray bottle with an electronic stethyscope to listen for the suction noise made when the water hits the leaking intake. It's quite accurate. The second item is the creation of phosgene gas, that happens when burning most spray cleaners into open flame. Dont remember which component in the aerosol causes it but it is really deadly so please be in a well vented area if using this procedure. If you get even a tinge of sting in your nose leave the area quickly.
Bill