I think spoilers should be used only when asked for by the OP, etc and not too freely.
I usually take a printout of answers that I find useful, or too dense. Printouts have spoilers as blank text Edit: Aryabhata has suggested stackprinter app which works
It does not show underlying text on mobile touch based devices (ipad, etc) so to read such answers while commuting, I have to click on edit, look at the source, and exit without saving any edits.
(Spoilers are not proliferate in the main site yet, but I asked this question as I noticed a problem and wouldn't want it to become a bother later.)