According to interpretations of Maryland Code, Real Property, Section 8-203(f)(1)(i): "Even in the absence of an express covenant, the law imposes on a tenant the obligation to return the premises at the termination of the tenancy substantially in the same condition as when he received possession and to restore the leased property to the landlord at the end of the term unimpaired by the negligence of the tenant. A tenant, however, is not liable for damage to the premises ensuing from a reasonable use or for damage caused by the elements."
An individual I'm working with had approximately 90% of their security deposit withheld based on dust and/or minor stains to several sections of their rented area. According the the evidence provided by the landlord, these situations were resolved by readily available and low-cost cleaning products, but the landlord opted to charge a flat penalty based on an agreement before the lease, for cleaning charges which were not tied to any specific level of damage nor made any reference to what effort nor supplies were required for the cleaning.
The wording of the interpretation of Maryland Code, Real Property, Section 8-113 and Maryland Code, Real Property, Section 8-203(f)(1)(i) could favor the landlord, given the wording of the contract. However this individual believes that matters such as dust (in areas such as on a bedroom windowsill or on bedroom baseboards) or non-permanent stains (i.e. a maple syrup drop in the refrigerator, or a fingerprint on a bathroom mirror) can be could be defined as "wear and tear" as defined in Maryland law, and thus the room is being returned "substantially in the same condition as when he received possession and to restore the leased property to the landlord at the end of the term unimpaired by the negligence of the tenant".
A case like this seems like it could go for either party. Are there any more definitive guides on which party may be in the right here? Is there any legal precedent that could determine if this is a case worth pursuing in a court of law? It seems like there could be some clarification to assist this based on the legal definitions of "damage", "unimpaired" and "substantially" per the cited interpretations, but I'm personally unsure how to proceed to advise in this case.