I do not wanna make this thread as long as the week before the pay-day, but
I've learnt some performace slow-downs with the use of COUNTIF and SUMPRODUCT
approach. The paging is slower and my PC is not exactly the slowest one.

However the SEARCH works great. How could one use it to highlight the entire
row if a value of any cell (given either by column enumeration or a subset)
equals exactly to '?' (question-mark sign).