You can't ever look like you're too interested or too professional.
I haven't always worn a suit to interviews but I've always worn a tie.
I supervise a bunch of guys but I still work with my hands every day too. Had a special event at my daughters school last night and I hung out in the hallways with all the dads in cartharts and work clothes. I'm most comfortable in that crowd and there's a feeling of mutual respect seeing a guy in work gear.
But if a guy shows up for an interview in that or jeans,I think he really didn't want it bad enough to buy a new shirt. I don't care about a suit and tie other than it tells me he wants it bad enough to dig through his closet and dress up.
I agree with bentruler. I was going to recommend the exact same thing last night but ran out of time. Although coming from me is coming from a guy who has never been on an interview.
When in doubt always dress more up than down. The only disadvantage to dressing up too much is it shows in inabilty to read social situations well, and that may be something they are looking for. It is ideal to dress appropriately rather than overdress. Show up to interview with me in a tux and I'll think your not all that people smart, even though you may be a great mechanic.
Wear what you would wear for the job or slightly better as others have suggested. Based on the interviews I've given recently, a few applicants might've done better if they followed these suggestions: If you have any earrings or piercings, by all means take them out. Excessive or offensive tattoos should be covered up. Don't take a smoke break while filling out the app. Don't talk too much, don't complain about your past jobs too much. Be on time to the interview. Don't stretch your experience too much or they may expect you to actually be able to do what you say you can. Make sure you look clean/clean cut.
JMO Dress ready to work. Your clothes should not be ratty or dirty. Service Work: You will be going to someones place of buisness or home. Dress appropriate to mix with public and not wear offensive clothing ie.. holes or improper phrases imprinted on your tee shirt. Contract Work New: Less neat is OK but you need to dress OSHA safe.
Dressing like this says your ready to go to work right now!