I have run into a lot of the wrong dentists. If they are not willing to talk to you to explain things, FIND SOMEONE ELSE. I do have periodontal disease and believe I need deep cleaning because of this. They need to keep bacteria away from under the gums. It's not a mess, or painful, but they do use novocaine. With dental care, you want to prevent future problems, all of which can cost a fortune. Infections under the gums can transmit bacteria to cause heart disease, so its nothing to fool around with.
Since they are all telling you the same thing, you could try it. It will probably cost less than having your whole mouth done. It's very important to find a dental office where you feel they are honest and courteous. Hugs!