I don't think there's any way of rating this, really, since so many different factors come in to play.
What kind of mood am I in? What time of the month is it? Like most women, I have a one week window where just looking at my clit is almost enough to make me break the headboard in half... And then a few days where I'm more likely to grow wings than I am to orgasm. Mother nature is a cruel fucking bitch, trust me...
There's also the matter of the well meaning guy who just has no clue what he's doing. Now, if he's willing to listen and take direction, that can be solved fairly simply, but some stubborn bastards are stuck in a press button 'a', tweak buttons 'b' and 'c', insert, remove, repeat rut. That's fine - but if that's your groove, don't sulk if we politely answer 'no' when you ask us if you made us come.
As well, 'enjoying' ourselves and climaxing are often two different things. A session can be enjoyable even if the magic button didn't get pushed, and there have been guys who've made me come that I still hope never darken my doorway again.
That said... ideally I
always want to come (and the more the merrier!), because I'm a greedy fucking bitch, and have always assumed that you guys are there to amuse
me for an hour or so
Morgan