As you already know, from being "deaf", you can put your hand on the drive occasionally and feel for the click... if there is one.
As a general rule, a failing hard drive does NOT have a click as it begins to fail... that is usually limited to certain Hitachi, older Maxtor, and Tri-Gem models. The Western Digital, Samsung, Fujitsu, and Seagate hard drives rarely click, if ever.
Also, many clicking drives just click... and keep on ticking... but are fine.
When you have a drive you think is going, run the drive fitness test found on the manufacturers website. If the S.M.A.R.T. test is positive, you have at least an 86 percent chance that the drive is perfect... but probably closer to 97 percent. Every hard drive manufacturer except Tri-Gem and Toshiba have a drive fitness test on their website... and they usually complete their test if less than five minutes.
Good luck to you.