Yes carburetor cleaner and starter fluid are both bad for use on any gasoline engine especially 2 cycles. To me if it won't start on what it is meant to run on then there is a problem. Even starter fluid on diesel can make them dependent on it like a drug addict.
Now with some handhelds just be aware that the old magnet pointing to the coil trick don't always apply. Stihl 4 mix and Shindaiwa C4 for examples align differently so you must verify the flywheel key if you suspect ignition timing problem.
Personally I don't trust those inline testers. If suspect a coil of being weak then an end of the line spark gap tester should be used. That should eliminate any false readings though it doesn't test the plug itself.
For inline testing just use your wife or kids for you might get just as good results.
Just plain shocking and mean. Just indicates voltage is present but not how strong; although, a smack across the chops might be a good indication.
The truest measure of society is the how it treats its elderly, its pets, and its prisoners.