Bedroom problems and sofa issues

Isla the Lurcher is now a much-loved member of our family but we're having a few problems and I'd be grateful for some help, please!
Like most Lurchers, she loves comfort and likes nothing better than getting on the sofa, which is fine in our house - our sofas are very dog-friendly!
However, when we go visiting it's not always appropriate for her to assume she can sit on other people's furniture! I struggle to get her off which is embarrassing.
Also, when she goes upstairs she likes to get on the beds - which again, is fine with us. It's just on the rare occasion when we don't want her to get on the bed she isn't at all happy about getting off.
If you tell her to get her off the bed, she refuses. If you try to touch her collar and make her get off she'll growl and pretend to bite you which I think is obviously totally out of order.
I just don't like the fact that no one in the family can grab her collar in an emergency without a tantrum. What should we do?
My reaction when she tries to bite is to shout loudly at her and then take her downstairs and shut the stair gate, but it doesn't seem to be working.
We've tried training her with treats to get off the sofa and bed but it doesn't seem to work as she's not that bothered about food and very often we don't have food to hand when we need to get her to do something.
Help!
Kevin Brockbank, Newbury

I'd train the dog to settle on a particular blanket - which can then be put on the bed or sofa. Then, when you visit friends, take the blanket and put it on the floor, so Isla rests there, rather than on the sofa. When training, practise the recall and touch her collar briefly every time she comes and then give her a treat. When she sits for a squeaky toy (this may work better than a treat, as she doesn't sound food-oriented), then touch her collar and then reward. Little and often, touch her collar to help desensitise her - so she realises it's a good thing, not a threatening gesture. The emergency grab is something that is taught at Puppy School - it's a godsend. It's a pity Isla's too old for Puppy School classes, but some training with a good behaviourist sounds vital. Oh, and stop shouting at her when she 'pretends' to bite - you're reinforcing any idea she has that you are threatening her! She could well up the stakes and respond by really biting next! I think it was Dunbar who said a dog can go on the sofa and bed - no problem - but as long as that's okay with you and that he or she will get off when asked. Personally, I'd stop her having the sofa and bed privileges until your relationship is on a better footing, and instead give her a cosy crate where there can be no dispute and to defuse any problem situations. A good behaviourist could sort this out quickly and nip any future problems in the bud, A worthwhile investment now, at the start of your relationship, I'd say. Claire Horton-Bussey