Tobirama has stated repeatedly that he does not have anything in particular against the Uchiha.
(He lies. They bother him more than other potentially mutinous clans.)
There is just something off about a clan that seems to value power above all else.
(He knows but will never admit that the Senju are much the same.)
Their eyes are creepy and filled with dangerous fire.
(He conveniently ignores the colour of his own eyes.)
The way they operate with blind passion is disgraceful for a clan that prides itself on its sight.
(He will never admit that he is, in a way, envious.)
Notes: I'm not so keen on this one. It's a bit unsure and shaky.