Initial prep always pays in the end.
I did a fleece myself last night in the washer. Spread out the fleece and remove all tags and shorter length staples.
Separate fleece into workable bunches. Open the fleece up (use a picker or by hand). The more you open & fluff the fleece the better the detergent can get in and dissolve the lanolin & dirt (and a lot of VM falls out). Open the cut end and the tips. Yes, it's time consuming now, but you'll have a much cleaner fleece and less work later on.
Dissolve your detergent in your washer (I use regular laundry detergent at 2-3 times the recommended amount plus add some borax since I have hard water). Fill machine with HOT water. Turn off the machine Add your picked fleece bunches, pushing them under the soapy water. Close the lid and let soak for 30 minutes. Put on spin (hopefully your machine does not shoot water during the spin cycle).
Remove and examine fleece. Open up more tips, pick any VM you can. Repeat soaking with detergent (use less than the first load).
When fleece is clean, do one more soak, but this time no detergent and a few glugs of white vinegar.