I am wondering if there was a site set up where landlords in certain towns/cities could go on and leave info about tenants that have been a problem, can we be charged for slander. I mean reading all these questions and responses on here makes me wonder if we worded thing correctly, and they were real situations we had with tenants, then how can it be slader because we are being honesto

I found this on a Canadian Law site and reading through it makes it seem like there are loop holes for landlords telling the truth to each other.

Truth - A statement may have hurt your reputation, but if it was true then anyone can say it and have a good defence against a lawsuit.
OAbsolute privilege - There are two main examples of this defence:
1.statements given in evidence at a trial, and
2.statements made in Parliament.

This defence also allows the fair and accurate reporting of those statements in the media, like newspaper reports of a trial. People must be able to speak freely in our justice and political systems, without worrying about a lawsuit when they do so.
OQualified privilege - If your former employee gave your name to an employer as a reference, the potential employer may call you. You say: "He was unreliable poor at his work and I would not hire him again". As long as you acted in good faith, the defense of qualified privilege protects you if the former employee sues you for defamation. You had a moral duty to give your honest opinion and the caller had a legitimate interest in hearing it.
OFair comment - We all are free to comment, even harshly, about issues of public interest, as long as our comments are honest, not malicious, and based on fact.

Someone else will come along to address the specific legal aspects, but as I understand it, slander is spoken, libel is written. ;)

I know that, but if you are being honest an d doing for the good of another person it is OK...

I don't think there is such a site. Usually a prospective landlord will CALL up the prior landlord and talk to them about the tenant's ontime payment of rent and if the tenant was a good or bad tenant.

Some large landlords may report problem tenants, especially when the problem is late payments, to credit reporting bureaus.

There may be localized sites that allow landlords to report problem tenants. See if there is a local landlords association in your area.

But truth is a defense against slander and libel. But a) you need to have concrete proof and b) you may still have to go through the expense of a trial.