I recently had a synthetic carpet with several milk spills in various parts of the lounge carpet.
(a 4 year old)
wasn't told and very slight visible stains so went ahead and cleaned the carpet in the usual way,
prey spray, agitation ,and hwe.
All looked good, but towards the end the smell got worse and worse and was not noticeable when I started,
continued to dry pass several times, no improvement. So beware even if it looks good the smell can be a nightmare. took a return visit and another go at it and then it reduced did not eliminate