Are you speaking of the performance or aesthetics or both? I assume both since you're using both interchangeably.
Its not as if its intrinsically bad in giving Joker tattoos and modifying or adding to his already unique look. Ayer's alteration was no different from Nolan's in that he modified the Joker in accordance to the particular tone and world he was aiming for. Honestly, I don't feel as though Leto himself was even the issue as he is a capable and versatile actor in addition to physically fitting Joker the most, more so than his predecessors . It may simply have been a combination of execution and script.
I think Leto is more than capable of delivering a good, even great, Joker performance, but I feel his Joker had many setbacks, from design to writing.
He had a lot to say in the movie yet at the same time, he said nothing, Heath's Joker delivered more intimidation with a look, whereas I found myself more... confused (?) when Joker made an appearance in SS.
Could have been editing, too, I've seen the movie a few times and I still don't even get wtf happened in that club scene, that had to be poor editing or poor writing, or both, but I don't put that on Leto
I don't mind tattoos on Joker, I don't mind a more gangster look, but I do mind him looking like a fanboy Joker cosplayer because of the choice in tattoos.
Too clean, too obvious, too "flash tattoo"
if it looked like it was carved in his flesh, hurried, messy, okay, but "damaged" on his forehead because Batman made him sad?
Come..... on.