Does a Landlord's claims mean obligation to pay?

Ok I have recently got a letter in the mail from my old apartment complex. The letter is from a collection agency stating $60 in charges. The landlord claimed I had damaged the blinds and stained the carpet. The carpet was already stained, and the blinds were just replaced for no reason. I have no proof of this. They have no proof I “damaged” them either, other than the word of their $10 per hour maintenance man (who is probably instructed to replace random stuff).

Basically does the mere claim of the landlord constitute proof that I damaged the apartment. I am about to dispute the charges with the collection agency (I have 30 days to do so). I have already placed several internal disputes with the complex, but to no avail (as they have obviously sent my “debt” to collections).

What should I do about these cutthroats? Should I send the complex a resquest for proof that I have made the damages and if they can not provide such proof and do not pull the debt from collections I will legally retaliate?