This is very often I see on ICO group with members around 50,000 But message/day is only around 20-30, of course this is very suspicious compared to the real telegram group, only about 4000-8000 members are active in the chat. I think this is not entirely wrong from the ICO Team because they usually paid services to individuals or groups but of course it's not professional.
Everyone knows that most ICOs do offer some airdrop for telegram members and that is always going to mean that people who are not really interested Join. JUst judge as investor the face value of that.