In any case people at trade shows need to be engaged by booth staff.
It really seems to be a cultural thing. If booth staff over here would act
like this, a small minority of people would perhaps like it, but the huge
majority would be driven away from the booth by it. Here the general
rule is not to talk to a potential customer unless he turned towards you
and made eye contact.
I remember a book fair where I walked up to a guy browsing one of our
books and said hello. He turned around, snapped "****, are you blind,
don't you see that I am reading ?", put the book back on the shelf and
left, obviously quite angry.
At another book fair we could only afford a very small booth, about the
size of a prison cell, and we spent some time at the much bigger neigh-
bouring booth - especially after my colleague had counted the visitors
at our booth and found out that more people browsed our books when
we were not there and only went over whenever someone began to look
around for staff.