Mould is often a tenant issue though, not a landlord issue.
It certainly can be a tenant issue, but equally, it can often be an issue with agents.
Our current house is susceptible to damp, and therefore to mould. A few months after we moved in, I pointed out to the agent that a large bush growing right up against the house seemed to have a lot of earth around it and might have to do with the damp problem on the inside of that wall. A few months later I looked again, and found that if I cut back branches, I could see that earth had build up until it was above the level of the damp course. I phone the agent again. After that I removed as much earth as I could (and it took ages because the bush had rooted into the ground every few inches and I had to hack it back). Now I've found the bush is growing through the brickwork in several places.
The agent's response? 'Oh, are you sure? I never noticed? I'll send someone out at some point.'
I'm not holding my breath to be honest.
We've also told them about the missing tiles where the birds are getting in, and the leak in the toilet cistern, and the badly-fitting windows and doors, and the fact that the unpainted window is slowly decaying (I can't repaint it myself; it's a casement that needs removing).
Our agents seem very nice people, but I do often find that agents don't have much interest in keeping the fabric of a property in good order.