Served as an E for 10 years, 3 of those as PO (which has now been done away with). I only served in one congregation so this is not an over-all view. All recomendations were prayed over and then compared to the scriptual qualifications in Titus and Timothy. Most of the time the BOE was unamious but if one E had reservtions then the recomendation was held off till the next CO visit and the brother with the reservations was assigned to work with the brother in question in what ever area that needed improvement according to the above scriptures.
Any who qualified were then presented and discussed with the CO during the next visit and he usually agreed. The recommendations were signed and sent to the society and usualy returned approved. After the society's appointment letter was recieved we would met with the brother under prayer and asked him if there was any reason he could not accept his appointment. The society didn't however give the new servant his assignments, that was done by the BOE after meeting with him. We usually loaded him up with assignments... lol.
I must say, at the time, I felt the HS was involved (at the congregation level) as long as we prayed and went by the scriptural qualifications. I have been out of the loop for 6 years now and some things have changed, new E book and now no letter sent to the society because the CO decides.
For the most part everything went smoothly. I did however see some nepotisim (spelling?), favortism or mild repression due to personality conflicts but nothing to serious. It was easy to become a MS but much more difficult in making E, in our congregation. I steped asside when I started having doubts about my qualifications, baiscally burnout and pressing finacial issues. Have no desire to try to qualify again and the gap gets wider every day. Most men who want to be E have no idea what they are getting into and looking back I wished I never did. A lot of my time was sacrificed for trivial matters when I should of spent more time with my family.
As far as "deceptive Es" it does happen but I would say it is not the norm. However good Es do what the society tells them, no questions asked, feeling secure in their actions being in line with "Jehovah."