What about a product can irritate you?

When I had some Monster cables with their "turbine" connectors they loved to try to pull out the RCA's they were connected to. Gave those away to someone who I wasn't real enamored with - let them make his day!
Having black-on-black writing on the back of pre-pro's is always fun, as my close vision distance is getting more challenged by the day, and not having contrast on the input naming sorta completes the challenge. I got a couple of those miner style lamp headbands so I can make out the lettering.
Unreliable - Yamaha - my old DSP 3090 spent more time in the shop than my old Alfa Romeo, and Pioneer - I gave away my DV47 when it just decided to give up the ghost - too many times in the shop for that too. No more Yammie or Pioneer for me even for third or fourth systems.

My biggest are too-coarse or too-fine volume controls and tempermental remotes. The sticker on the CD edges also get to me so I echo Edesilva on that one.

I agree with Edesilva,that little strip of wonder tape on CDs drives me nuts !!!

In relation to TimF's complaint about wandering input selectors, I owned a Jolida integrated that featured a input selector that "wandered." That is, it never seemed to know where the precise setting for any particular input was. It sometimes seemed at rest, then a channel would drop out. I had not experienced that sort of shoddy construction previously (or since).

The "Standby / On" toggle switch on the back of Joule Electra Vamp is located waaaay to close to the right speaker cable binding posts. Oh well. It sounds good, so I deal with it...