When I went through the processes it was not actually as bad as I thought it would be. A very long form to fill out, then an investigator is assigned. Or multiple investigators if you have lived in various areas. They will talk to your neighbors, co-workers, and friends for several years back. They will check with law enforcement where ever you have lived. One's experience with it seems to depend somewhat on the investigator assigned. The interview with my investigator was not bad at all. I have heard stories about investigators who are jerks, but that was not my experience.
A person does not have to have a perfect life for a security clearance. Past illegal drug use does not put one out of the running. One of the fellows in the same group I was in did a lot of weed--but had cleaned up several years earlier, was honest about it all and he got in. Another fellow had been arrested before (but not convicted), via a psycho ex-girlfriend who had falsely claimed abuse, but he just told his side of the story and he got in. If you have meaningful connections to foreign countries, currently do drugs or have a drinking problem, have significant financial problems, have been convicted of crimes, have something that you could be blackmailed for, or are deceptive in the process, you will have a rough time.
If the job is interesting and if you are a decent person, then I would give it a shot.