Is there really no such thing as a stupid question?

I am not sure I believe that there are no stupid questions. During the last couple of weeks I’ve fielded quite a few that qualify as such.

The first example comes from the people working on renovating my condo. Unfortunately, most of the questions they ask qualify as stupid for the simple reason that I have already answered them multiple times and in multiple ways. This most recent question that I had already answered involves paint. Per their request, I picked out the paint for the ceiling, wall and trim in the hallway, paid for it and brought it to my house. I placed the cans of paint in the living room, inches away from the path that the men will take to get to the hall, and labeled the tops of the cans “ceiling,” “wall,” and “trim.” Yesterday, I arrived home to find a laundry list of questions including, what color do you want us to paint the hall and where is the paint?

The next example comes from the people who are conducting some animal experiments that I need for graduate school paper #2. I sent my strains to our collaborator with documentation describing the genotype and phenotype of the strains, including a formally written note included with the shipment, an email informing them that I sent the strains and what they should expect to find in the package in addition to labeling the actual strains. This is what you need to know about the strains:
Strain 1: ampicillin-resistant
Strain 2: ampicillin-susceptible, kanamycin-resistant

A couple of days after our collaborators receive the strains, I get this message:
Microbiologist XX,
I think something is wrong with the strains that you gave me. I streaked them out on ampicillin, but only one of them grew.
Sincerely,
Animal Collaborator

I respond with a nice email explaining that every thing was fine and only one strain should grow on the ampicillin. I also describe the relevant characteristics of each strain again.

A couple of weeks later I get this email:

Microbiologist XX,
Are you sure that both of your strains grow aren’t resistant to kanamycin? When I streak the amp-resistant strain on plates containing amp and plates containing kan, it only grows on the kan plates. When I inoculate the strain into broth containing kan or broth containing amp, it grows in both. Are you sure that your amp-resistant strain isn’t also kanamycin resistant?

Again, I respond with a nice email explaining that no, there is no way that ampicillin-resistant strain is also resistant to kanamycin. I tell them that I think they are introducing a contaminant. I ask them to check the original stocks for growth in the presence of amp or kan and to let me know if the strains grow in the presence of an antibiotic they shouldn’t grow in. I haven’t heard anything since.

I don’t mind answering these questions. In fact, I am glad that they are asking me questions when they run into problems, but at the same time it worries me. If you can’t keep a stock or culture free of contaminants then how can I be sure that the data you send me reflects my strains and not my strains plus some other random contaminant? Is sterile technique really that hard?