The mechanical ones I bought for less than a dollar a piece are fine enough for user interface. I'll make some videos hopefully today.
Mechanical encoders have their place, and opticals have their place. I have designed a welding machine that used 10 of the $2.58 mechanical encoders and the users loved them. Previously they had used optical encoders and they were almost useless. For an operator input the small mechanicals fit the bill well. for motion monitoring the optical encoders are much better.