Battery fumes

looby lou

I am due to pick up our first ever motorhome next week, whilst I was doing a inspection and test run I noticed a strong smell of battery fumes in the liesure battery storage area.  With todays sealed batteries I was under the impression that they should
not produce/vent fumes unless they had failed? please correct me if I am wrong.  I was not convinced that the problem was taken as serious as expected it should be.  I would rather buy a new battery than take any chances of failure.