Watson woke with a start to find Holmes clad in a rude sailor dress with a pea-jacket and coarse red scarf. (The Sign of Four) 

 

When Holmes returned home after sending a telegram to Athelney Jones, neither Jones or Watson recognised him. He was described as "an aged man, clad in seafaring garb, with an old pea-jacket buttoned up to his throat. His back was bowed, his knees were shaky, and his breathing was painfully asthmatic. As he leaned upon a thick oaken cudgel his shoulders heaved in the effort to draw the air into his lungs. He had a coloured scarf round his chin, and I could see little of his face save a pair of keen dark eyes, iverhung by bushy white brows and long gray side-whiskers. Altogether he gave me the impression of a respectable master mariner who had fallen into years and poverty." (The Sign of Four)

 

The day after the first visit from the King of Bohemia, Watson was at 221B Baker Street waiting for Holmes to return when "the door opened, and a drunken-looking groom, ill-kempt and side-whiskered, with an inflamed face and disreputable clothes, walked into the room."

It took Watson a few looks before he was sure that it was Holmes. (A Scandal in Bohemia)

 

Holmes needed to enter the house of Irene Adler and this is the disguise he choice to use. A broad black hat, baggy trousers, white tie, a sympathetic smile and a general look of peering and benevolent curiosity. "His expression, his manner, his very soul seemed to very with every fresh part that he assumed." (A Scandal in Bohemia)