A lot of people, follow different spiritual schools and Gurus. I had a chance to discuss with them about their Gurus teaching and how they felt after attending these lectures.  
Listening to different peoples experiences made me think and I was able to draw few common key themes like :
  • "Guru ji is so knowledgeable and such an eloquent speaker that just listening to him/her brings calmness".
  • "Guru ji's / Spiritual Organization's satsang (chanting sessions) are so good, I feel uplifted".
  • "Guru ji has great knowledge of scriptures, he is so intelligent and well read. I am so impressed with his/her speech. I never thought about this topic this way".
Does this sound familiar? There are a lot of people out there that attend these sessions and events and spend a lot of money on them to feel good.
After hearing them, I always ask them these question -
  • How is your state now?
  • Do you feel  the same way as you felt then?
  • If you need to be in that state again, do you have the tools and techniques ?
  • Do you feel that this Guru can help solve your relationship and financial issues?
  • Do you feel that this Guru can guide you to achieve ultimate goal?
  • Do you feel that, these events teaches you techniques that can help you achieve permanent happiness?
These events/ lectures reminds me of my college and school days. Like any young kid, I use to be very fond of music and would always love to attend rock concerts. I would feel elevated/happy/excited when I use to see my favorite singers performing live. I would hear their song on a CD to attain a similar state.

A lot us feel good and relaxed when we hear certain type of songs/music/movie/tv series, but once that stops we get back to our "status quo" / current state. So basically the effect of listening to these spiritual lectures and attending rock concert/watching a tv show is same.

Hopefully now you can distinguish between an Entertainer and a Guru.