I've used consumer marketed "shampoos" (think Bissel branded etc.) and various carpet/upholstery products marketed for automotive purposes, but I haven't found any that work any better (or perhaps as well), or as cost effectively as traffic lane cleaners (TLC) and upholstery cleaners sold through janitorial supply/commercial carpet cleaning supply stores.
The most important step is thorough removal of any remaining "soap" residues. That step cures a lot of ills.
Assuming you are speaking of biokleen product, I'm a big fan! Use it for spotting as well as a laundry additive. I just wish I could purchase it locally by the gallon. I pick it up 4 qts. at a time when I can find it sale priced on-line.
Bio-Kleen products
I have never taken this extra step. For automotive carpets (my own residential carpets as well) I stress proper matting. Most of the vehicles I see have leather upholstery. BUT, I have just added a new vehicle to my personal stable which has fabric upholstery, so I am interested in the possibility of adding some protection. Do you use the aerosol based product or the liquid spray? How effective is it? How long does the application last (typically)? Have you seen any adverse fabric reactions (I recognize the need to test first -- so just in general)?
Do you use the aerosol based product or the liquid spray?
I have 'leather' uphostered cars now, don't see many fabric seats now. I used to use an older aerosol version (once this is used up I'll buy liquid spray type.
How long does the application last (typically)?
Very hard to say as I don't have a way to test its 'life' but I used to apply it every few months.
Have you seen any adverse fabric reactions (I recognize the need to test first -- so just in general)?
None that I remember