Mr Seldom Bucket is the former cheese-producer and dairyman who now owns the Ankh-Morpork Opera House. Previously renowned for his Lancre Blue, he is now regarded as the unfortunate soul who took on not one but two Opera Ghosts during the events of Maskerade.
Bucket is a business owner above all else. While he is in fact a fan of both opera and cheese, he sees each of these primarily a means to an end, that end being money. In the dairy business, he wasn't bothered by selling the batch of strawberry yoghurt which was inadvertently and inconveniently polluted by the severed finger of an employee. Similarly, Bucket was pleased to cash in on the spate of grisly murders, rumors of which caused the public to flock to buy opera tickets.
Bucket believes that he can determine a person's character by looking him (always him - women seem to flummox him completely) in the eye and shaking his hand. This despite all evidence - he did not recognize the disingenuous salesmanship of the previous owners, he didn't figure out the subterfuge of his most trusted employees... Those who perpetrate opera may be poor actors, but even they managed to fool Seldom Bucket.