I think it all depends on personal preference. The problem with addressing people as "dear"; "love"; "girlie" or "my lover" or whatever, is that you do not know what people's personal preferences are. Therefore, to be polite, you should use a neutral term with strangers, preferably one that sounds respectful - "sir" or "madam" and so on.
And yes, helshea - people could easily say "dear" without being "nice and friendly". A lot would depend on how they said it.
I hate unequal naming. For example, one visits a doctor, who introduces him(it usually is a "him)self as "Dr Smith", then proceeds to address you by your first name, despite the fact that you are old enough to be his mother or gran!
Yes, it can be said that this is just to be friendly. But the reality is that it confirms the inequality of the relationship - "me -important doctor; you - not so important patient".
My favourite doctor always addressed me formally, until I asked her to call me by my first name. She then told me hers.