In short, no, especially in orthodox conversions today. However, I think that is generally true in all the movements.
If your sponsoring rabbi recommends to your beit din that it is time for you to take the oral examination part of your conversion ("the" beit din) and your beit din agrees, then you likely ARE ready. And it reflects their idea that even if you turn out to not be ready, you WILL be ready eventually. You should be a Jew. After all, do you have any idea how hard it is to get three people (no less three rabbis!) together in one place for an hour or more? My conservative beit din was (supposed to be) my rabbi and two congregants. Even without dealing with three rabbis, it still took two and a half months from "you're ready for us to convene a beit din" to finding a date convenient for all four of us, plus the congregational mikvah lady. It also had to be rescheduled at least once!
As described on the Conversion page: [The beit din is] very similar to the way the computerized GRE works today: if you get an easy question right, they'll keep going to harder and harder questions until you don't know any more. It's an effective way to discover the limits and holes in your knowledge. There's nothing wrong with those limits or holes. No Jew ever knows everything. One of the most important things a beit din needs to know is that you are able to admit what you don't know and that you know where to locate an answer. For instance, when you finally have to say, "I don't know," they may next ask, "Then how would you find out?" And sometimes, the answer is as simple as "email my rabbi"!
However, it may happen that the beit din realizes during the conversation that you have an area of knowledge that really needs to be explored before conversion. After all, they can't know how well you know all of it until you actually sit down together and have that discussion. In that case, they will tweak your learning plan and make arrangements for a second beit din meeting in the future. Because of this, you will always be warned before the beit din that you shouldn't expect to go to the mikvah that day. However, they'll also tell you to prepare in case you do go to the mikvah that day!
Today, the process is changing so that you'll go through several of these "conversations" with your sponsoring rabbi (and probably even with the full beit din!) before your conversion. It sounds frightening and soul-crushing (particularly to those who who fear public speaking), but personally, I think this is one of the better changes in conversions today. Even if your sponsoring rabbi and beit din don't have this as a set policy, you will certainly be allowed "test runs" if you ask for them. In fact, that is yet another way to show your sincerity and dedication.
So to tie it together: even if your first meeting with the beit din doesn't result in your conversion, you have not failed. The fact that you got there in the first place says that they all believe you should become a Jew. You just might not be to the "right" place yet.
Now some practical advice: Don't tell anyone (other than the people closest to you, if you so choose) when you get a beit din date. In the unusual case that they decide you aren't ready yet, you don't want to have to explain to every third person. Therefore, I suggest only telling people you would be comfortable telling that the beit din said you're not ready. The last thing you need is everyone asking, "So, what's it like to be Jewish now? How was the beit din? What was the mikvah like?" and you have to explain that you weren't ready. There are few things as frustrating as thinking you'll be done, and then you aren't. Don't compact the pressure.