I've read enough about wishes to know you have to word them very carefully. :-)
True true true. Wishes are interesting things, and if you delve into several world myths you will notice an interesting trend. That of wishes being used by capricious deities to destroy those that they would wish to destroy. Careful wording is extremely necessary, otherwise one would gain their wish .....and find it fulfilled in a way that makes them scream bloody murder.
For example those that wish for immortality. There is a geek myth of a man being granted that, but being given a disease ridden form that is aged and crippled, and thus having to spend the eons in blinding pain. Thus he was given immortality, but it was a form of hades.
A more well known example is that of Phrygian King, Midas. The whole tale about the golden touch and how his greatest desire (being able to substantiate anything into gold by touch) actually destroyed his TRUE greatest blessing (his daughter, who was turned into a splinking sparkling golden statue through an accidental touch).
There are other legends of people asking for omniscience, and once their wish is granted they spend the rest of their lives in misery as all that knowledge enables them to know what true suffering is.
Maybe the most interesting is in the form of a cartoon. I believe it is Alladin 2: The Return of Jafar (I'm 80% sure it is from that movie cartoon). Anyways this bad dude gets the lamp that imprisons Jaffar (who had been turned into a genie in the first movie, when he made the mistake -AGAIN through making a stupid wish where he asked for unlimited power, and thus was turned into a genie, with the sligh addition that genies had to be imprisoned to have ultimate power). Anyways, this guy gets the lamp and Jaffar (in genie form) asks him what he wants. 3 wishes. The first wish the dude makes is to get immense wealth, and in the flash of a second he is teleported into a sunken galleon at the bottom of the sea. Now, the guy has gotten his wish ....astounding wealth and treasure .....but he is no drowning, and thus needs to use his second wish to ask to be taken to dry land. Now, he has already used 2 wishes and has nothing to speak for them apart from some wet clothes.
Again, wishes can be fickle things. For example wishing to meet one's true love. If it is granted in a skewed way this might mean literally meeting them ...for a second. For example meeting the love of your life in the arms of another. Or in the freeway where your eyes lock for a second before they whisk off. It is not specific enough.
Oh, and I think the worst wish of all would be the whole 'unlimited wishes' thing. The evil genies and capricious demi-gods must have some really special mad mojo waiting for anyone who asks for that one. Some really nasty mojo. LOL.
And the final thing is probably that all the wishes that people have can be realized. All that is needed is for people to live by design instead of just wafting through life. Refusing to settle for just anything has this funny knack of allowing someone to fulfil their purpose. Everyone can get their heart's desires.