I take a couple of my dogs to lots of places but always ensuring they are actively welcome first because its no fun if they aren't (even though both dogs would just lie on their mats, which I bring with me, and not move if thats what was required).
I don't allow children or dogs into my home - its a risk I won't take due to the dogs I have and some of their past experiences.
You have several options though, depending on your own pets.
You explain that your pets will be distressed by a dog running about, if their dog could be crated in your kitchen or living room (again depending on what pets YOU have and where you'll be for the visit) so it is not running about - that might be acceptable, but the dog must be happy about being crated not whine and cry the whole time.
Or, you'll come and visit them.
But, you say sweetly 'I know you will understand how important our animals needs are and see why we have to put our xyz animals needs before our own desire to have visitors'...
Chances are they will not want the bother of training their dog to be crated, of carting a crate about, and will just invite you over to them.