Do I really need deep cleaning?

My gums are pink and do not bleed from brushing or flossing and I have a few 4's in the back.  I do have some irritation from irritating crown margins and hypersensitivity to dental materials.  Why do dental hygienists push for deep cleaning?  Have it done, they say, then come back every 3 months for a cleaning instead of twice a year.  I'm always told I have hardly any tartar.  Is it the extra money?  I worry about getting any infection from previous patients because no matter how clean they try to be, there is always contamination and HIV is a big worry now.  I ordered a Hydro Floss oral irrigator and highly recommend www.mamagums.com  who is a dental hygienist who is big on baking soda, peroxide, and oral irrigators.

[catnip009]

Well, I had the deep cleaning done and it was an expensive waste of time.  I think it's just a scam to make a lot more money.  She only did a couple of teeth in each quadrant and decided they were less than 4 mm deep.  2-3 is normal. She really could find any "pockets" so I am wondering why she kept pressuring me to have it done$$$$.   But I did research gum disease and as a result learned that what I have are chronic allergic reactions going on around my metal crowns that can mimic gum disease in appearance.  And I bought a Hydro-Floss oral irrigator as recommended by mamagums.com and I love it.  Just remember not use it above a "5" setting and keep it moving while bending over the sink.  People with gum disease report pockets healing up.