I think you're being a little unfair to Esperanto. Of course there are words in every language which look or sound like rude or amusing words in English. The word 'penis' which you cited simply means '(somebody) tried'. For a fair introduction to Esperanto, go to www.lernu.net. Esperanto works! I’ve used it in speech and writing - and sung in it - in about fifteen countries over recent years.
Indeed, the language has some remarkable practical benefits. Personally, I’ve made friends around the world through Esperanto that I would never have been able to communicate with otherwise. And then there’s the Pasporta Servo, which provides free lodging and local information to Esperanto-speaking travellers in over 90 countries. In the past few years I have had guided tours of Berlin and Milan and Douala in Cameroon in the planned language. I have discussed philosophy with a Slovene poet, humour on television with a Bulgarian TV producer. I’ve discussed what life was like in East Berlin before the wall came down, how to cook perfect spaghetti, the advantages and disadvantages of monarchy, and so on.
Of course Esperanto cannot compete wwith English but it remains useful and has a steady speaker population, with people happy to meet and talk to you and me in places where it would be hard to find a speaker of English.
Now, was I making a little fun of Esperanto? Yes, of course! IMHO, Esperanto is one of those hobbies that you kind of need to have a sense of humor about. And I'm not saying that in a mean-comment-hey-can't-you-take-a-joke sort of way. As someone who has starred as a Romulan in a community-cable Star Trek parody series, I mean it in a sincere gentle-ribbing-among-friends kind of way.
Frankly, there's a limit to how many people you'll attract by taking Esperanto's noble purpose too seriously. However, you can make a very strong case for the claim that Esperanto is fun! And the Esperanto community is fun too, isn't it? Allow me to quote the letter that Esperanto's inventor (Ludwik Zamenhof) composed and encouraged people to send to their friends:
Vi rigard-os la sub-scrib-o-n kaj ek-kri-os: "Cu li perd-is la sag-o-n?"
Which translates as
You will look at the signature and cry out, "Has he lost his mind?"
So, a little light-hearted self-deprecation has been part of Esperanto's marketing strategy from the beginning, and is probably one of the main reasons that Esperanto is the most successful invented language ever. Go to the lernu website and try it out!
p.s. On a totally unrelated note, this other website has guessed that my blog is "probably written by a female somewhere between 26-35 years old. The writing style is personal and happy most of the time." Exactly what I wanted to hear on my thirty-ninth birthday! I hardly feel a day over thirty-five. :D