I often see players asking questions about the effectiveness of Stealth, Master of Deception (MoD) and the Night Elf Shadowmeld abilites (Active and Passive). In particular, there's a common misconception that certain ranks of MoD provide no additional benefit over the previous rank. I took advantage of the extended Stress Test weekend to level up Rogues on two accounts so I could run some much needed stealth tests. Hopefully the screenshots below answer many of those questions. All tests were performed with level 14 Rogues (5 talent points) and all screenshots were taken at the exact distance that the opponent would come into view.
Night Elf Shadowmeld (Equivalent to Human Stealth with 0 MoD)
Night Elf Stealth - 0 MoD (Equivalent to Human Stealth - 1 MoD)
Night Elf Stealth - 1 MoD (Equivalent to Human Stealth - 2 MoD)
Night Elf Stealth - 2 MoD (Equivalent to Human Stealth - 3 MoD)
Night Elf Stealth - 3 MoD (Equivalent to Human Stealth - 4 MoD)
Night Elf Stealth - 4 MoD (Equivalent to Human Stealth - 5 MoD)
Night Elf Stealth - 5 MoD
Human Stealth - 0 MoD (Equivalent to Night Elf Shadowmeld)
Human Stealth - 1 MoD (Equivalent to Night Elf Stealth - 0 MoD)
Human Stealth - 2 MoD (Equivalent to Night Elf Stealth - 1 MoD)
Human Stealth - 3 MoD (Equivalent to Night Elf Stealth - 2 MoD)
Human Stealth - 4 MoD (Equivalent to Night Elf Stealth - 3 MoD)
I ran out of gold and time to test Human with 5 MoD, but following the trend above, it would have been equivalent to Night Elf Stealth with 4 MoD.
For more information about effects that impact your stealth level and stealth detection level, check out my Stealth Chart.
