Despite the few interactions between Splendid and Mole, it is shown that they are not fond of each other, likely due to Splendid's impatience and Mole's blindness always clashing, generating a conflict. It could be argued that their conflict is one-sided, as The Mole shows less signs of disliking Splendid than vice-versa.
Splendid is shown to harbor great contempt towards Mole. Though it isn't certain when or why this started, it is first shown Gems the Breaks as Mole becomes his first intentional kill and only intention kill that was out of personal anger and not to defeat a criminal. In See What Develops Splendid gets very annoyed at being paired with Mole and when he got a picture of him changing out of his reporter personnel, Splendid goes to very great lengths to try to stop and possibly even kill him.
It is hard to tell what exactly Mole thinks of Splendid. In one hand, in Gems the Breaks Mole became annoyed at Splendid's laser beam slowing down traffic and honked at it (though it is unknown how he knew it was there in the first place). In the other hand, Wrath of Con shows him attending Splendid's speech implying he may be a fan.