Traditionally, ambiguous exclusion clauses provide little or no protection because they will be interpreted narrowly and against the person who tried to exclude their liability (in Latin the contra proferentem rule).
In the light of modern methods of interpretation it is doubtful that this principle of interpretation can be used in every case for anything but guidance.
Where the clauses appear in commercial contracts between sophisticated parties, ambiguity will be resolved by looking at the context and purpose of the agreement rather than by applying narrow principles to the words used.