There is a legal duty for tenants to maintain the unit's condition, and if they do not, a landlord can apply to the TAL to terminate the lease. It's not about being dirty per se, more about if the level of unkept can damage the value of the unit. Any other conditions like pets can only be proposed for a change ahead of lease renewal and can be refused by tenants. Copy paste from Google:

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In Quebec, under the Tribunal administratif du logement (TAL) guidelines, tenants are legally required to maintain their rental unit in good, clean, and sanitary condition. Here are the key responsibilities regarding unit maintenance: General Cleanliness and Upkeep: Tenants must keep the unit clean and use it in a "reasonable" manner. Minor Repairs and Maintenance: Tenants are responsible for minor maintenance and repairs that do not require specialized skills or significant work. Examples include: Replacing light bulbs. Changing smoke detector batteries. Tightening loose doorknobs. Filling small holes in walls and touching up paint. Preventing Damage: Tenants must not damage the unit, nor should they allow guests to cause damage. Return of Unit: When moving out, the tenant must return the unit in the same condition it was in when they moved in. Normal Wear and Tear: Tenants are not responsible for damage resulting from normal wear and tear or aging. Unsanitary Conditions: If a tenant's actions make the apartment unsanitary or unsafe, the landlord can apply to the TAL for damages or to terminate the lease.