My experience (over 20 years of at least three Open Days per year, plus hundreds of admissions interviews) is like that of @Etulosba's. I work with a great team, in a good university; in past jobs, I've also worked in terrific departments at excellent universities. Most universities & departments in this country are excellent - we are not a mecca for overseas students for nothing. I think that MN offers a very negative & distrustful view of UK universities, often based on one or two incidents in a poster's DC's degree. Compared to many other countries, UK citizens are really lucky in our university system - the quality is comparatively even across all institutions, and we still have a lot of permanent staff (cf. the USA, where quality is hugely divergent, and the employment of academic staff increasingly precarious).
So it's not 'hard sell' - it's trying to work out what a potential applicant is interested in, and letting them know what we offer that they might find sympatico. That's why parents participating in that sort of conversation can be counter-productive. We need to hear the potential applicant and what they're really interested in.
In fact, so far do I back away from hard sell that when I ask a potential applicant at an Open Day which aspects of my discipline they are particularly interested in, I will recommend other departments in other universities which might match their interests/ambitions more closely than my own institution. Any good academic knows what goes on elsewhere in her discipline.
I think part of the perception of 'hard sell' is that often pupils at school are so on the treadmill of assessments, exams, grades etc etc - from the age of their first SATS tests at around 6 or so? - that they need to take a pause and think about what they really want to do - not what other people expect of them.
But we always have current students to talk to potential applicants - and we don't tell them what to say. They are really good people for DCs to talk to.