Appreciation and Criticism are equally problematic

While talking about the qualities of a Gyaani-Bhakta, Lord Krishna says:
                        समः शत्रौ च मित्रे च तथा मानापमानयोः 
                        शीतोष्ण सुखदुःखेषु समः सङ्गविवर्जितः  
                                                  भगवद गीता 12 /18 
             "Samah shatrau ch mitray ch tathaa maan-apmaanyoh
               Sheetoshna sukh-dukheshu samah sang-vivarjatah"
                                                        Bhagavad Geeta 12/18
He, who is same to foe and friend, and also in honor and dishonor, 
who is the same in cold and heat, in pleasure and pain, who is free from attachment. 

The same sentiments are echoed in the Gurubani by the ninth Guru:
                       सुख दुःख दोनों सम कर जानै, और मान अपमाना 
                        हरख सोग ते रहै अतीता तिनि जग ततु पछाना 
             "Sukh dukh dono sam kar jaanai, aur maan apamaanaa
              Harkh sog tay rahai ateeta,tini jag tat pachhanaa"
                                                                    (SGGS page 219)
(One who knows that pain and pleasure are both the same, and honor and dishonor as well
Who remains detached from joy and sorrow, realizes the true essence in the world.) 

Why all Holy Scriptures advise us to stay from the above mentioned sentiments?
Let's try to understand these human emotions separately and how they play important role in our lives - especially for the seekers of spirituality. 
First: let's take the sentiments of Maan and Apamaan - mentioned in the above phrases from both scriptures; the Bhagavad Geeta and the Gurubani. 
Seemingly meek and the mildest of all the above, the sentiments of Maan and Apamaan; Respect and disrespect- appreciation and criticism – honor and dishonor - approval and disapproval or admiration and condemnation are equally - or perhaps more problematic, and can affect the Gyanis; the wise ones as well. 
Favors, praises, approvals, admiration and honors lift us up - while criticism, disapproval, disgrace and condemnation knock us down. 
In fact, either one of these sentiments depends on the opinions of others. If we depend on the approval and disapproval of others then our happiness and sadness would also depend on others. 
When our state of mind is affected by other's admiration or criticism then we lose our equilibrium.
It causes us to depart from our center. 
                              'Rajan Sachdeva'
                                          'To be continued'