This is the kind of little issue that I know only bothers web designers, but I believe has larger impact in terms of the tone set by developers with respect to the customers.
Step 1. I open an email from ACTIVE, a deal of the day type subscription for triathlon gear, and I click a link in the email to something I might buy. At this point the marketing team has done a splendid job getting me to open their email (mostly because of a too-good-to-be-true subject line) and even click a link from the email, hooray conversion!
Step 2. The link tells me "You've requested the desktop site, but you appear to have a mobile browser."
Your email was well formatted for mobile (kudos for the that), what are you expecting me to open emails on?! And you are the one who requested that page, not me!
This issue comes up all the time with broken internet connections. The copy always seems to read: "couldn't download, you disconnected from the internet". Screw you, I didn't disconnect from anything! My computer did, but remember, developers, you are writing an error message or alert not to the computer but to the user! Please, please remember that, and stop using such presumptive and accusatory language in your error messages.
(We can talk about how strange it is that you have different mobile/desktop pages later, that is another issue.)