Unfortunately, in present day society in the name of suddha-bhakti various types of mixed devotion such as karma-misra (mixed with fruitive action), jnana-misra (mixed with speculative knowledge) and yoga-misra (mixed with various types of yoga processes) as well as various polluted and imaginary conceptions are spreading everywhere like germs of plague. People in general consider these polluted and mixed conceptions to be bhakti, respect them as such, and thus remain deprived of suddha-bhakti. These polluted and mixed concepts are our greatest enemies. Some people say that there is no value in bhakti, that God is an imaginary sentiment only, that man has merely created the image of a God in his imagination, and that bhakti is just a diseased state of consciousness which cannot benefit us in any way. These types of people, though opposed to bhakti, cannot do much harm to us because we can easily recognise them and avoid them. But those who propagate that bhagavad-bhakti is the highest dharma yet behave against the principles of suddha-bhakti and also instruct others against the principles of suddha-bhakti can be especially harmful to us. In the name of bhakti they instruct us against the actual principles of bhakti and ultimately lead us onto a path which is totally opposed to bhagavad-bhakti. Therefore, with great endeavour our previous acaryas have defined the svarupa or intrinsic nature of bhakti and have repeatedly cautioned us to keep ourselves away from polluted and mixed concepts.

(From Bhakti-tattva-viveka, by Srila Bhaktivinoda Thakura)