I don't expect they can do any better a job cleaning than you can at home if you really put the care and effort into it. ; If you just are doing a quick-n-lazy cleaning, that's a different story. ; Personally, I have a 3-step cleaning system, of which 75% of the time, I use only step 1, 20% of the time I go to step 2, and only 5% of the time do I use the full 3 steps.
Step 1 - Bulb blower. ; Hold camera facing the opening down, insert blower tip without touching the sensor, give some nice strong squeezes to the bulb, with a little time in between each blow for the air and any removed dust to settle out. ; Works most of the time for light dust.
Step 2 - Sensor brush. ; Fine soft bristle brush designed for sensors. ; Spin or shake brush before use to 'charge' it. ; Brush gently across the sensor, brushing in the same direction. ; No pressure needed - it picks up any dust from a slight charging of the bristles. ; Works most of the time for the more stubborn dust that wants to cling to the sensor and resists the bulb blower.
Step 3 - Wet swab. ; Not necessary too often. ; Swab and cleaning fluid plus some form of applicator wand. ; Wet swab with cleaning fluid (using the more sensitive E2 fluid usually is best). ; Swab should either have a dry side, or a second dry swab ready. ; Swipe wet swab across sensor face with light pressure. ; One swipe only. ; Then reverse swab or get dry swab, and swipe across sensor in the same direction as the wet swab. ; Should get the last of any stubborn dust and any wet or sticky dust or specks that have gotten on the sensor plate.
As for calibrations/adjustments/etc - I suppose those could go off after a while, but I would think you'd only need to worry about it if you had reason to suspect your camera wasn't metering properly anymore. ; Personally, I haven't had metering go off on a camera before. ; Focus too can go off, and if you don't have micro-adjust capability in body, that may need to be sent in for adjustment as well. ; Luckily, I haven't had that issue either with any bodies so far.