Even if they cleared all the clutter, cleaned that kitchen top to bottom, it still wouldn’t pass.
I agree cleaning isn't enough. Even if they got professionals in there's a good chance the score would still be low, as hygiene inspections don't just look at cleanliness. They also want to know about:
Food storage - You can't store products you're selling in a communal kitchen fridge.
Safe food handling / preperation - For example how they will avoid cross contamination.
Compliance with the necessary regulations / Risk assessments - Food labelling, fire safety, COSHH etc
Pest control (including less obvious things like insect screens on the windows)
Ensuring there's adequate facilities for cleaning, disinfecting and storing utensils, including equipment.
Knowledge about food safety protocols / procedures
Any training that has been undertaken and proof of this.
The hygiene of those working with the food.
The access (or lack of) in the house will also go against them, as it's a very cramped environment. By the time the inspector has made it from the front door to the kitchen the alarm bells will be ringing. As they will have squeezed past a moutain of coats, shoes and plastic storage boxes as well as seeing overfilled rooms and washing left to dry inside with the windows closed.