What are the makruh acts of wudu?
1) To consume more water than required while performing the wuḍū. This is based upon the tradition that the Messenger of Allah (saw) warned Ṣaʿd (ra) who wasted water while performing the wuḍū and told him to avoid such waste even when performing the wuḍū on a riverbank.
2) Washing the limbs by literally hitting the water on the face or other parts of the body. Such an action will cause the used water to splash the clothes, and this would be against the good manners of performing the wuḍū.
3) Talking unnecessarily while performing the wuḍū.
4) Asking someone else to assist and pour water without a necessity.
5) To perform the wuḍū in an unclean and dirty place.
6) To embellish the maḍmaḍa and istinshāq while fasting since, in such acts, there is a possibility of breaking the fast.[1]
[1] Ibn Abidīn, ibid, I, 121-123; al-Shurunbulālī, Marāq al-Falāḥ, Maṭbaʿat al-ʿilmiyya, Egypt, 1315, p. 13; al-Dirdir, al-Sharḥ al-Kabīr, Egypt, n.d., I, 126-129.
Source: Basic Islamic Principles (ilmiḥal) According to the Four Sunni Schools With Evidence From The Sources of Islamic Law, Prof. Hamdi Döndüren, Erkam Publications