Sheikh Abdul-Aziz bin Abdullah bin Baz (commonly known as "Bin Baz") has been described as the "figurehead of institutional Wahhabism", was one of the most prominent proponents of the Salafi ideology, and was the vice-president of the Islamic University of Madinah. In fact, in the 1990's, he was the Grand Mufti of Saudi Arabia - the single most influential Salafi religious authority, appointed by the country's tyrannical "King". The country's Grand Mufti is also granted presidency of the Permanent Committee of Islamic Studies and Verdicts - whose members are drawn from the Council of Senior Scholars (Saudi Arabia's highest body of religious clerics). In a question and answer session, Bin Baz has been recorded here controversially revealing his Fatwa (verdict) permitting the innovated "Al-Zawaj Bi-Niyyat Al-Talaq" (literally: marriage with the intention of divorce), also known as Nikah Al-Misyar (marriage of the traveller). This marriage involves a man deceitfully marrying a woman, while intending to divorce her at a later date. The condition for this marriage to be lawful, however, is that the man MUST NOT reveal his intention, and the woman must be under the impression that their marriage is indefinite. If the man does reveal the marriage's expiration date to the woman, then this would fall under the Shia Muslim practice of Mutah (temporary marriage) - which, although allowed by the Messenger of Allah (peace be upon him and his family), was banned by Umar bin Al-Khattab, and therefore is considered to be Haram (prohibited) by "Sunni" Muslims.
We find it truly ironic that Salafis are usually the first to attack Shia Islam for permitting Mutah (temporary marriage) - a marriage just like the usual permanent marriage (with a dowry given to the wife, etc.), but with both parties agreeing upon an end date. In our day and age, it is most commonly used amongst Muslims as a Halal (lawful) means of getting to know a potential spouse, before their permanent marriage.
The opposers of the Shia are very quick to attack the legislated union of Mutah (temporary marriage), yet permit Al-Zawaj Bi-Niyyat Al-Talaq (marriage with the intention of divorce), which is a clear innovation, and is obviously not based upon any Quranic verse, or Prophetic tradition. Not only this, but they also have several other questionable forms of marriage.
Such examples include Nikah Al-Misyar (marriage of the traveller), but another controversial example is known as Jihad Al-Nikah ("sexual Jihad"), which many Salafi scholars have also permitted. A quick internet search will reveal to you these forms of marriages permitted by "Sunni" religious authorities. Another such example is the consequence of Umar bin Al-Khattab's innovation of "triple Talaq (divorce) laws", known as Nikah Halala. It is essentially a sham-marriage, where a woman pays a man for sexual intercourse - which even prompted the BBC to report on it in a recent news article. These are just some examples, to name a few.
Yet they attack Shia Islam?