If I know a piece of information that my competitors which is false to a potential buyer, am I allowed to let that buyer know when it’s to my benefit that they don’t buy it?
There are five conditions to saying Recilus L’toeles, and the fact that you are a competitor, will only change things slightly. The first condition is that your main intention is actually for toeles, and not for your own gain. The fact that you are a competitor, just means that you will have to work on yourself more, to concentrate and make you intention for the other person’s toeles, and not for yours. The other conditions are, that what you say has to be 100% true, and that you aren’t adding anything to make it sound more than what it really is. Additionally, that you are not allowed to exaggerate the point. This are things that you can do even if you are a competitor, although you have to be extra careful with yourself. The next condition is that you don’t have any other way to let him know this, and usually there isn’t any other way to inform him. And the fifth one is that you are not going to cause the other person any extra harm. Therefore, make sure that he doesn’t go around spreading it to others.
When these conditions are met, you can tell him what he needs to hear.
Chofetz Chaom -Rechilus Chapter 9.