SeaFoam is a well-recognized product in the OPE industry. I have used it myself and found that it works very well on most occasions. Will it work in every situation? No. There are times when the carb must be dismantled totally and soaked for a couple of days in a true carb cleaner.
This often entails removing "frost plugs" that close off passages in the carb that are blocked solid with gunk. These need to be carefully rodded with fine wire so as to not harm any jetting and then blown out with compressed air prior to returning the carb body to the cleaning solution so it can finish the job.
None of the above is meant to take anything away from SeaFoam because it often will do the job on its own. But if it doesn't work to your satisfaction, don't blame it and say that it's worthless. Every product has its limitations. SeaFoam is the first thing I reach for and if the problem persists, then "cooking the carb" in cleaning solution is the next move.
If the SeaFoam does clear it up, then look at all the time you saved.