AMERICAN UNITED TREE SERVICE

These folks had done some tree trimming for me before (apprx. one year ago), which had to be redone due to lousy workmanship [this company solicits work door-to-door while driving through neighborhoods].  On this occassion, they came to my door and asked there was any tree trimming I needed and I told them that I would like for them to remove a limb that they had trimmed improperly previously, a simple task that I could have done myself, but I succumbed to letting them do this since they hauled off the cuttings and I had numerous other tasks to complete around the house that day. 
Prior to giving them the go ahead to trim off the limb, which was a least a foot in diameter, I told them to make sure that they cut the limb in a way that it would not tear the bark below the cut when the limb fell.  They told me they were good at what they do and not to worry about the bark being torn or the concrete driveway being cracked from the falling limb.  Luckily the driveway was not damaged, but the cut they made was not done properly and when the limb released from the cut, it pulled off at least a foot of bark below the cut exposing the inner bark ("the pipeline through which food is passed to the rest of the tree" - source: Arbor Day Foundation). Now, at a minimum, I will have an ugly scar on the tree if bugs and moisture don't get to it first!

I strongly recommend against using this fly-by-night tree trimming service and to stick with larger, more reputable firms.