Somewhere, Anthea is laughing at John.
Part 2: [link]
Part 4: [link]
That experiment I guess is to determine "the pattern a blowtorch makes on various metals" which isn't a wise thing to do on a bed or a kitchen counter.
Deleted scene: Sherlock and Sherry end up subconsciously wearing the same/very similar outfits everyday until John shouts "Well, ONE OF YOU is going to have to change!"