Not the main indicators to measuring the project, but you can use telegram to find out how active they are and how to know the responses from other community.
There are lots of active channels and groups that mainly uses a bot for their telegram accounts . so depending on it wont still guarantee you a succesful ico .
I believe the success of ico cant be found on how active their telegram or any other platforms but the success does trully comes from the usefulness of their projects.
Overall , finding a good and legit ico can still be a tough job due to the many competitions thesedays.