After Eliezer returned with Rivkah as a wife for Yitzchok, the Torah tells us, "And Yitzchok brought her to his mother Sarah's tent; and he took Rivkah as his wife" (Bereishis 24, 66). Targum Unkelos explains that Yitzchok saw that Rivkah's behavior paralleled his mother's behavior and only then did he take her as his wife.
In the previous pasuk the Torah states that Eliezer told Yitzchok everything that occurred to him. Rashi explains that Eliezer related the numerous miracles that had occurred in the course of his finding a mate for Yitzchok: the earth contracted to allow him to arrive at his desired destination quickly, and immediately with the conclusion of his tefillah his prayers were answered in the most amazing manner. If so, asks Rav Wolbe (Shiurei Chumash) quoting the Brisker Rav, what more was needed to prove that Yitzchok and Rivkah were literally a match made in heaven? After hearing about the miracles that brought about his prospective match, why did Yitzchok feel compelled to also examine Rivkah's actions before agreeing to marry her?
The answer is that even if there are earth shattering events that all point in the direction of a specific match, nevertheless, the deciding factor must be the woman's middos. Likewise, in the beginning of the parsha when Eliezer wished to find the proper wife for Yitzchok, he prepared a test to determine the quality of her middos. The Torah true way of checking into a shidduch is by determining the manner in which the prospective spouse conducts himself/herself.
There are many things - and maybe even miracles - that have the ability to make us lose focus of what is truly important. However, we must always bear in mind that "derech eretz kadma l'Torah" - good middos preceded and are the foundation for the Torah. Moreover, they are the foundation of the entire Jewish Nation, because our Patriarchs looked for good middos when choosing a mate to build their families and all future generations.