Do you think it's unethical to go for a job interview while you don't want it? (Or it's like you're 90% sure that you don't want it.)
Do you think it's wasting the interviewer's time?
Or you think it's just okay?
I'll be thankful if you share your experiences about this.
A trial is a trial.
You might decide it's not a good fit.
After the trial, you can apologize and say you don't think you are a good fit for the company at present time.
Make sure you are genuine with your apologies and stay on good terms. You never know, you might work for them in the future.