It depends. I rarely get them these days.
My cousin got one. He told the guy he had the wrong number and then sent him a picture of him and his wife wearing cow costumes. The whole conversation was posted on facebook and was quite hilarious. Apparently these guys had a mutual friend but he texted my cousin in error.
My friend started getting phone calls and texts to her phone from a school just outside of our district. There were texts and messages about kids. She called the school and explained that she was getting these messages instead of them reaching their intended destination. They were pretty important so the call to the school was in order.
Now... I get TONS of emails not meant for me. I get statements from AT&T, receipts from people's online purchases, etc. I've even received log-in information for people's different accounts with places as well as reminders about doctor's appointments, newsletters from schools, you name it. I mean, probably 40 emails a day are for someone other than us. It makes me CRAZY! The longer we have this email address the worse it has gotten. We've had this email address since '95. I hate to change it because we have had it for so long and people know how to reach us here, but my gosh am I tired of other people's emails (and receiving really personal information as well). I delete the junk emails but if it seems personal or important I email back saying they have not reached their intended recipient. AT&T still can't get the crap straightened out. The email address is our last name @ provider. I think a lot of times people probably have email addresses with an initial before the same last name but the initial gets left off and we get their email. Or they think they have the same email address we do... I don't know? I've stopped using that account for sensitive information though because if we get all of this, are some of ours going elsewhere? Not sure.