Hi there!

While it's not my intention to be combative, can you cite any contemporary sources claiming Umayyad decadence from the 8th century? Virtually all the critiques historians have of the Umayyad caliphates are derived from Abbasid sources, and so should be examined more carefully since the two were potent adversaries until the total collapse of the Umayyad Caliphate outside Hispania and ascension of the Abbasid caliphs.

To your point, the Umayyad's were more accused of misrule rather than decadence, and then again only towards the end of the 8th century. Hisham ibn Abd al-Malik, the 10th Umayyad caliph, was thought of as very capable. Umayyad caliphs were specifically accused of making Arab Muslims preeminent in Islam contrary to the Prophet's teachings, of not energetically promoting the conversion of People of the Book - namely Christians and Jews - in favor of their lucrative jizya tax, of failing to stem the Byzantine threat, and of allowing tribal factionalism to divide the Islamic world. After the Umayyad army suffered a crushing defeat to the Byzantines in 718, many began to question whether they were still divinely led, though this may be Abbasid propaganda.

Regardless, I am not equipped to mount a defense of these particulars of the Umayyad caliphate in Damascus. But I do not believe 'decadence', in the modern sense, was part of the contemporary anti-Umayyad narrative.