Deposit disputes rarely turn on the obvious. Agents inspect against an inventory, and the items that fail are almost always the ones a normal weekly clean never touches.
Ovens are the single biggest cause of deductions, followed by extractor filters, limescale on shower screens, window tracks and the interior of kitchen cupboards. Each takes specialist product and time.
Photograph the property once cleaned, keep your receipt, and make sure the clean is booked after the last item of furniture leaves. A clean carried out around belongings is impossible to sign off.