Some time ago I bought a tablet for my mom. Since she regularly needs support, TeamViewer QuickSupport it's a must. It works very well with all Android devices I own so far, except that Asus tablet. Because they are greedy and they only offer it for business customers! So I returned the tablet the next day.
After this bitter experience I remembered that I have another Asus product: AC-RT66U router. Which looks great if you look at the specs sheet and even in benchmarks, but in real-life usage it sucks. Has compatibility issues with most Apple products and any other products that copy them (like LG smartphones). Signal is weak and throttles a lot because it gets hot. It is set up to restart weekly in order to make it work.
It's pretty clear that for me, Asus is a brand I will avoid.
Update 2019-03-25 Asus servers were hacked and hackers were able to push malware signed with Asus certificates as updates to Asus software.
Update 2024-05-14 Asus is extorting people to pay for microscopic scratches in order to cover the warranty claims. (covered by Gamers Nexus, Louis Rossman comments)