There is a skill to cleaning sensors, particularly wet cleaning. I've learned to use very little eclipse on the swabs, and It always takes about 5 swabs to do a good job.
Eclipse is merely super clean acohol and does not leave sticky residue. However, a poor cleaning will smear any oil or lube that is on the sensor or picked up by touching the mirror box with the swab all over the sensor and make it worse.
Unfortunately, cameras sometimes have too much lube in the mirror hinge, and it leaks onto the sensor and makes it difficult to clean. If that is happening, send it to canon or it will splash lube on the sensor over and over. Dust sticks to the lube.