Carpet cleaning and pest control should be specified in the tenancy agreement.
A lessor/agent can specify that carpets must be cleaned or pest control carried out to a required standard, if that was the standard at the start of the tenancy.
If pets are permitted, additional pest control may be specified in the agreement, e.g. flea treatment.
Tenants should be aware of their carpet cleaning and pest control obligations at the start of the tenancy.
If there is any doubt over whether the carpets were cleaned before the tenant moved in, the lessor/agent should be able to prove this.