"The signature of G-d is truth." (Shabbat 55b) As beings created in the image of G-d we too are expected to be the epitome of integrity. Lying or misrepresenting oneself earns one not only moral opprobrium but has legal implications as well. 
"Be betrothed to me with this cup of wine yet it is honey, with honey but it is wine...on condition that I am wealthy yet he is poor, on condition that I am poor yet he is wealthy she is not betrothed." (Kiddushin 48b) 
Jewish law voids any and all contracts signed under (material) false pretenses. How much more so is this true in a marriage contract where honesty is the building block of the relationship? 
"Rabbi Shimon says if he tricked her for the better they are married."  While Rabbi Shimon also accepts the concept of a mekach taut, a mistaken and thus void transaction, giving someone honey that turns out to be wine or being wealthier than advertised is presumably something one would be pleased to discover. One may be willing to marry a person of limited means but surely one would be happier with a little more. 
Nonetheless the Sages disagree, voiding a marriage even in such a scenario. A mistruth is a mistruth even if no harm is done and even if one benefits. While Jewish law recognizes that at times lying is permissible[1] or even obligatory such is not the case when signing a contract and surely not when entering a marriage. 
Alternatively it could be that the Sages actually agree with Rav Shimon. Getting more than one bargained for is wonderful. But it is not at all clear that greater wealth is a blessing. Marrying someone of greater means may not be the wisest thing to do. The wealthy, understandably, have expectations that someone raised in a lower economic sphere may not be able to meet. It is for good reason our Sages recommended that one marry in the same socio-economic class. In addition wealth itself can often be a curse and we are all witness to those who have changed for the worse upon acquiring great wealth. "Who is wealthy? One who is happy with his lot." (Pirkei Avot 4:1) And with "increased wealth [comes] increased worries." (Pirkei Avot 2:7) Wealth is not for everyone and the halacha understands this very well. 
Of course the definition of wealth itself is somewhat subjective. "On condition that I am wealthy we do not say [he must be as wealthy] as Rabbi Eliezer ben Chirsom or Rabbi Elazar ben Azaria[2], rather anyone who the people in his city honour him due to his wealth." (Kiddushin 49b) Little has changed over the years.
Increased wealth may desensitize one to the needs of others. The Talmud relates that when Rabban Gamliel arrived at the home of Rabbi Yehoshua to apologize for publicly embarrassing him he remarked "from the walls of your home it is apparent you are a blacksmith to which Rabbi Yehoshua replied "woe unto the generation which you are its benefactor as you do not know [understand] the pain of [needy] Torah scholars." (Brachot 28a) Is it any wonder our Sages are not at all certain that marrying a much wealthier person is a 'mistake for the better?'
If it is difficult to assess wealth it is even harder to assess character. "On condition that I am a tzadik, righteous, even if he be a rasha gamur, totally evil she is betrothed, perhaps thoughts of repentance entered his mind." (Kiddushin 49b) What a beautiful and most powerful teaching. No matter where one may be ethically one can always change for the better. Teshuva is a wonderful gift and a tremendous challenge. 
What is truly fascinating about this Gemara is the couple are betrothed despite the fact that there is no evidence that the groom to be actually did teshuva. There isn't even any evidence that he is thinking about doing teshuva. For all we know he is continuing in his evil ways. Yet the simple fact that "perhaps" thoughts of teshuva entered his mind is good enough to declare them legally married. His statement that he is a tzadik is taken at face value as evidence that he is on the road to teshuva. While he may misrepresent his wealth he will not misrepresent his essence - or so Jewish law declares.  
Of course what is true for the good is also true of its opposite[3]. If the evil can become righteous the righteous can become evil. Be betrothed unto me "on condition that I am a rasha, evil, even if he is totally righteous they are betrothed, perhaps thoughts of idolatry[4]entered his mind."
We all have such great potential. As we say during Netaneh tokef "until the day he dies I will wait for him and if he returns I will accept him immediately. It is never too late to change. We just m
[1] Interestingly a classic Talmudic discussion on the permissibility of lying is relating to the beauty of the bride where Beit Hillel allows one to extol the beauty of the bride even if one is less than enamored with her looks. As beauty is in the eyes of the beholder and since the bridegroom is marrying the bride he surely finds her beautiful - either literally or figuratively.   
[2] After Rabban Gamliel was (temporarily) deposed the rabbis rejected Rabbi Akiva as a possible replacement choosing instead Rabbi Elazar ben Azaria because "he is wise, he is wealthy and he is the tenth [generation descendant] to Ezra the scribe". While Rabbi Akiva was wise he lacked money and family status, which for better or worse are often decisive in gaining the respect of others.  
[3] What is true in the physical world is also true in the spiritual world, after all G-d created both. Newton's third law of motion, that for every action there is an equal and opposite reaction has its corollary in the spiritual world. The greater the potential for greatness the greater the potential for evil.
[4] While all sincere thoughts regarding mitzvot are credited to us only thoughts of idolatry are considered sinful.