This clause in your lease is dreadful, since it makes you financially responsible for the acts of people you may not even know. If the landlord is worried about common area damage, the solution is better vigilance and careful tenant screening. There's no way that you or any other tenant can effectively monitor the situation, since that would involve you in activities that tenants have no power to implement -- installing locks and cameras, hiring security personnel, and deducting money from the security deposits of tenants who cause damage, for example.

One wonders why you signed such a lease in the first place -- perhaps because there was so little housing available. Therein lies your defense if you are told to pay for repairs to common areas that you didn't cause: You were effectively forced to sign the lease with that clause, having no other options. In legalese, you were handed a contract of adhesion, which simply means that the other side had all the power and therefore no need to negotiate with you. This is what you can tell the judge when your landlord tries to evict you for refusing to pay.