We know Hanuman is covered with Saffron paste. But why is Ganesha covered with saffron paste. It is not seen in temples in southern part of India but most of the Ganesha's idols in northern part of India and all idols in the Ashta Vinayaka temples are covered with saffron paste. Why is it?
Lord Ganesha loves red.Red is the color associated with him.His body is reddish.He loves wearing red colored clothes.He loves being worshiped with red flowers and also being smeared with red fragrant paste.
Reference is verse no 11 in Ganapaty Atharva Seersha Upanishad:
रक्तं लम्बोदरं शूर्पकर्णकं रक्तवाससम् । रक्तगन्धानुलिप्ताङ्गं रक्तपुष्पैस्सुपूजितम् ॥
11.3: His Form is having a Beautiful Reddish Glow (Raktam), with a Large Belly (Lambodara) and with Large Ears like Fans (Shurpa Karna); He is wearing Red Garments (Rakta Vasam), 11.4: His Form is annointed with Red Fragrant Paste (Rakta Gandha), and He is worshiped with Red Flowers (Rakta Pushpa),
So,i think Ganapaty would love his body being smeared with Rakta Chandana(Red Sandal Paste) or even with Saffron(which is reddish in color)paste.
As explained in this answer, the white colour denotes satvva guna, the red colour denotes the rajo guna.
Ganesha is worshiped in southern parts of India but Sindoor (saffron paste) is not applied. But in North India, many temples are seen with Ganesha idols applied saffron. In Ashta Vinayak temples, all the Ganesha temples are applied Sindoor. Also there is a song praising Vinayak who applies sindoor(shendoor) in Marathi.
The reason behind this is that, all the idols in Ashta Vinayaka temples are self incarnated idols. Ganesha incarnated at those places to slay the asuras. Here Ganesha is worshiped by devotees for attaining bravery because he was furious while slaying different demons. When he kills Ugrekṣaṇa AKA Sindhu AKA Viprasādana in Mayureshwara avatar, the blood is spilled on him. That makes him happy. Here Ganesha shows Rajo guna. Hence Sindoor which signifies the rajo guna is applied to Ganesha idols.
You may notice that Sindoor is applied to Hanuman. It is only when He is worshiped in Veeranjaneya form but not when he is stood before Lord Rama or when worshiped in Prasannanjaneya(happiness) form.
This is the reason that Veerabhadra and Kalbhairava who are very well known members of Shiva gana are depicted saffron or red.
1.This is a custom to show the guna of the deity.
2.Sindoor applied to Hanuman has a story but lacks scriptural references. So this version is acceptable