With regards to the lead placement for a 12 lead ECG, I was taught the following :
Electrode Placement
V1 4th Intercostal space to the right of the sternum
V2 4th Intercostal space to the left of the sternum
V3 Midway between V2 and V4
V4 5th Intercostal space at the midclavicular line
V5 Anterior axillary line at the same level as V4
V6 Midaxillary line at the same level as V4 and V5
RL Anywhere above the ankle and below the torso
RA Anywhere between the shoulder and the elbow
LL Anywhere above the ankle and below the torso
LA Anywhere between the shoulder and the elbow
So with regards to the RL and the LL leads they can be place any where on the legs above the ankles but below the torso. I was taught to place them just above the ankles bilaterally, as you respect the patients modesty instead of placing it higher. So for me it would be socks off for an ECG. When I worked in A&E it was standard practice have the patient remove their socks or the pantyhose/stockings or roll up their leggings to have the ECG performed.
With regards to female patients and bras I was taught to have them remove them. For the modestly inclined patient I always provide them with the opportunity of having a female nurse perform the ECG. With regards to men , especially those with abundant chest hair I was taught to shave the areas required for the chest lead placement, which can lead to some very unusual patterns on their chest.
In my clinical environment ITU as our patients are naked under their gowns this is not really and issue with regards to the socks or pantyhose/stockings.