Red bugs are more common than most hobbyist understand, it takes a trained eye to spot them, a responsible hobbyist to treat them, and just when you think you have done everything to prevent from getting them back, you must treat again because they are there.
The truth is that, at this point it is my believe that 98% of all Sps keepers that say they never had them, actually do have them and just aren’t aware of it, fortunately treatment of this critters is somehow readily available and treatment is fairly simple to do.
My suggestion to spot this critters is to take a good macro pic of your sps’s and them look at them in your computer with a software that allows you to zoom on the branches,
If you need help, we have great resources in the Club to help you ID and treat correctly.