Plastering question - Please can you advise?

Hi - I am going to have my whole kitchen dot and dabbed this weekend. The plasterer has asked for some PVA to brush the walls down with before he applies the adhesive and boards. The walls are a mixture of old brick and stone and are currently very dusty. Even though he is going to apply the PVA on the day, would it be a good idea if i 'washed' down the walls with some diluted PVA before he arrives? My reasoning is that they are currently VERY dusty and endless brushing still breaks away the old gray mortar and dust. The kitchen is over 30 years old. Thanks in advance.