it isn't considered good form to(+ infinitive // example provided by ART Vancouver: 'I mean, when you've got used to a club where everything's nice and cheery, and where, if you want to attract a chappie's attention, you heave a piece of bread at him, it kind of damps you to come to a place where the youngest member is about eighty-seven and it isn't considered good form to talk to anyone unless you and he were through the Peninsular War together.' (P.G. Wodehouse))
