I'll second Susie on this one. There are two issues:-
1. The contact area is too small for such a sensitive location and the smaller the contact area the higher the stimulating response at any setting. This means that one 'step' between the settings can range from maybe no sensation to EeeeeeoW! I do use clips which have a very small contact area but these go on the outer labia which are less sensitive and there is a greater mass of tissue.
2. Pads, which are attached with an adhesive coating, will not stick reliably to a moist clitoris. They will peel off gradually, probably unnoticed, and as they finally part that last tiny contact will break with an unfortunate and unpleasant jolt.
It's far better, as Susie also says, to arrange for the stimulation to flow across the clitoral region. Do this with a pad immediately above the clitoris (low down on the pubis) with the other on the perineum - or a pad high up on each of the outer labia. You could also use a vaginal or anal probe as the other electrode.
The original question, from carrfear, referred to e-stim 'flops', i.e. not particularly effective or pleasant. Many people get nothing at all from e-stim or find it distinctly unpleasant. Many report "interesting but doesn't do a lot for me". It could be anything from simple antipathy to e-stim to the electrodes in the wrong place for that particular person.
Let me assure you though that in probably 50% of cases e-stim will be both effective and rewarding. Thats why I recommend you don't initially spend the 'couple of hundred' that carrfear did, but rather spend fifty on a simple TENS machine and pads. Most control boxes retailing for high bucks are nothing more than a re-cased TENS machine with a couple more knobs and programmes. See my e-stim pic at http://www.zity.biz/index.php?mx=gallery;ox=showitem;cx=3896;id=53846;sort=date;sorto=DESC That control box, the Sanitas SEM 40, has 50 programmes, 3 functions (EMS, TENS and Massage), 2 channels and cost Β£20 GBP (US$30) and does all I'd ever want or need. The ancillaries pictured are needed for whatever machine you buy and ebay provided all those for under Β£15 GBP (US$23)