if you are looking for a cat sitter, take a look the tips a cat sitter gave.

http://catsmammyhk.com/en/easy-3-ways-greeting-shy-cats/

Cats were definitely more vocal when their owners left compared to strangers....Here is my little tips

If a cat seems shy or aggressive then I approach them slowly, not looking directly at them.

-Get down to the ground to make myself smaller so I am never towering over them.

-Put my hand next to the side of their face so they can smell if the like

-Sweep my hand along the side of their neck and down their back with medium pressure.

Basically trying to let them know that I am in control of the situation so they don’t need to be nervous, and that I am not threatening to them by being slow and concise in my movements. This usually works with most cats but not all.