I've had Marine aquariums for over 25yrs my last one being 520 litres , a tank maintained properly looks fantastic 100% of the time but when not properly maintained they look awful except when freshly cleaned.
Most people love the hobby when first setting up the aquarium & getting new fish & coral etc but a month down the line when maintenance becomes a burden on your weekends the love can turn to hate.
I got rid of my last aquarium around six months ago & as much as I love the hobby I now just feel relief when I look at where the aquarium used to stand.