Using owl:sameAs in Linked Data

It's been a very long and interesting thread on Linking Open Data forum and elsewhere, about the use and semantics of owl:sameAs. I just suggested the following best practices :

1. Assertions such as "a:foo owl:sameAs b:bar" should be grounded on some form of agreement of the owners of a:foo and b:bar, on whichever basis they both decide to agree.
2. For outsiders (owning neither a: or b: domains), such agreement could be shown by the presence of the assertion in symmetrical way in both domains, each domain using its own URI/resource on subject side, and the other's on object side, that is :
   (a) asserts "a:foo owl:sameAs b:bar"
   (b) asserts "b:bar owl:sameAs a:foo".
3. If one side (a) pushes the assertion first, the other side (b) should be at least made aware of it by (a), and is entitled to say she agrees or not : (a) says that "a:foo owl:sameAs b:bar", but as the owner of (b), I do not necessarily agree. Such lack of agreement could be implicitly entailed from the absence of the reciprocal assertion on (b) side.

Granted, from a pure logical viewpoint, those assertions are strictly equivalent since owl:sameAs is a symmetrical property, but from a social/trust viewpoint, having each side declaring it in a specific direction could be interpreted as a formal proof of agreement. It's what have been done e.g. between DBpedia and GeoNames. The title thread shows once again by its sheer length, and if necessary, that there is no universal way to ground such agreement, which belongs to the realm of language and social communication.