Too many job ads are looking for insane amount of skills in one person...They ask for a "Unix Admin" person who knows how to code in C++, C#, manage an Asterisk server, install mange & tune 1000 RHEL servers, use NAGIOS, maintain a SAP system, automate sysadmin tasks using bash/ksh/perl/PHP/C/C++, setup and manage IIS & Apache, admin websphere & coldfusion, install manage and tune Windows 2003/2008/2008R2, manage VMware/vSphere/ESX/ESXi servers, perform second level support for Windows users, manage printers, travel onsite for servicing, be on call 24/7 (for no extra pay), and be able to interact like a jolly good fellow with customers, co-works and management, oh, and write documentation and explain things as well as Carl Sagan could.
I've seen this happen as a side effect of a formal job evaluation process. Employees write up their job duties/skills in minute detail ("I helped the SAP admin by rebooting a server once" becomes "maintain the SAP system") and these duties are then scored by a committee. More "duties" = more points = more money, so of course, the employee is entirely motivated to pad everything. My personal favourite is the educational requirements. I have a masters in an unrelated field, so therefore a masters is a "requirement" of my job that just happens to be worth 2 pay grades.
The evaluation committee normally does a pretty decent job of leveling out the pay grades, but unfortunately it's the originally document often turns into the job posting when that person needs to be replaced.