Recently interviewed an intern where they:

• did not have any commercial experience and was eager to gain it.
• lacked theoretical understanding of software engineering principles.

(I expected this)

But:

• arrived 35 minutes late
• Did not offer an apology or reasoning for being late

Since the individual was applying for an unpaid internship, I did not expect much, but it is still bothering me right now that they were 35 minutes late and gave me short notice. I basically feel that if they wanted to learn, they should at least show up on time. Aside from that the intern seemed pleasant.

Is it bad interview etiquette to dismiss somebody completely because they were late or is it better to rule it out as a one off and judge them on their performance at the interview?