Well, apart from six states that I mentioned, tribals from Uttarkhand and Himachal Pradesh also will generally be fair-colored. Some of the dark skin-color in the poor people is because they work in the sun all the time. I heard that the famous Bengali actress, Kanan Devi, was born in an untouchable caste. But I am not sure about it. Perhaps a Bengali member can enlighten us.
In Himachal and Uttarakhand many tribes are as fair-skinned as Kashmiris while Brahmins are relatively darker skinned. There is no way we can decide a person's caste by his/her facial features unless they are wearing some caste mark.
Yes Kanan Devi was untouchable. But then untouchability was not related to economic status of a person. For example Rani Rasmati Dasi a rich woman and 'untouchable' was patroness of Ramkrishna Paramhans a brahmin(who was dirt poor).
I cannot comment on other states but in my native village, there is a minor difference between upper and lower castes. I wouldn’t say that upper castes are all fair but the incidence of fairer and taller people is more common among upper caste groups while the incidence of darker people is higher in lower castes. But it’s not a hard or fast rule. There are many dark upper castes and there are occasionally some fair lower castes. I have yet to see any lower castes (I am talking about Dalits, not OBCs or middle castes) with sharp features though such as a hooked nose. There are stereotypes that have long existed in rural India of this nature and as they say, there is no smoke without fire.
It is not that easy to tell. There is a rough correlation between caste hierarchy and features/skin color, but it is not linear. Three upper castes make about 10% of Hindu population.
It is not easy to tell one's caste by name alone, unless one has a good knowledge of the local social order. People tend to jockey claiming higher castes than they are for status, but they also claim to jockey for lower caste position to get reservations.
Both of these men are former Chief Ministers of Bihar in Eastern India:
The guy on the left is Jitan Ram Manjhi who is a Mahadalit (I believe they are called Musahars in Bihar, can any Bihari correct me?) who are considered lower caste.
The guy on the right is Jaganath Mishra who is a Brahmin. Can anyone show me any Mahadalit/Musahar who looks like Jaganath Mishra. I’m sure there are some Brahmins who look like the individual on the left but not vice versa.
Dan Howard does not say why he started this discussion on color of skin with a casual post. I guess the same old Aryan-Dravidian theory of origin of caste system. It has been discussed enough & beaten to death in several other threads.
Maybe we should focus on other issues related to caste.