There is no reason to think that your money is going to pay the janitor.
Actually a percentage is used to pay the janitor. If the janitor were to be given a six figure salary than a larger percentage would go to the janitor and less to the rabbaim.
However, there are so many important causes to give to, and they are merely trying to stand out.
But they are just diverting tzedokah away from other organizations that are run more efficiently*. As a result less money is left for the true charitable use.
doing a mitzvah is great. getting others to do a mitzvah through yours is greater. therefore money that goes for advertising, is better than money that goes just for the cause, even if the “cause” money makes us feel better.
But they aren’t getting people to give tzedokah*, they are getting people who are already committed to giving tzedokah choose one organization (or cause) over another?
*I’m sure there are some who wouldn’t have given otherwise but the revenue generated from those donors are probably less than the advertizing campaign.