"When Longstreet was holding this brief independent command, a scout, more properly a spy, was placed at his service by the War Department. He was a man of about thirty years, calling himself a Mississippian, and was altogether an extraordinary character. He was paid in United States greenbacks. I approved requisition on the quartermaster every month for $150 for him. His time seemed to be passed about equally within our lines and the enemy's. Harrison (such was his name) always brought us true information. There was invariable confirmation of his reports afterwards.
"While always suspicious that such secret instruments give away as much as they bring and may be in the pay of both sides, it was difficult to be sure of this in Harrison's case. He went everywhere, even through Stanton's War Office at Washington itself, and brought in much. We could never discover that he sold anything against us; besides, we had means, and did verify his account of himself as coming from Mississippi. When Longstreet gave him up in September, he was sorry afterwards and missed the man. He made me try to get him back for our command, but I failed.
"There will be more to say of Harrison before losing him. On the whole he appears to have been a daring Southerner, hating Yankees most bitterly, but loving their greenbacks, and fond of secret, perilous adventure. Latrobe recently [early 1900's] heard from him in Baltomore, in want, and asking some small assistance."
Source: Recollections of a Confederate Staff Officer
Commentary
Moxley Sorrel's was known, among other things, for his distrust of spies. (He never referred to them as scouts except when in the presence of Longstreet.) However, with Longstreet's scout Harrison, his opinion appears to have altered over time as is indicated somewhat by Sorrel's account of Longstreet's meeting and employing him.