Dishwasher and ‘deep cleaning’

We have an integrated Bosch dishwasher (SGV4313GB/17) which has previously given trouble – the old “contents-still-dirty-at-the-end-of-the-wash thing”. We had an service guy round to look at it, and he diagnosed it as clogged-up pipework; he showed me the pipes before cleaning them (yuk) and that certainly did the job. He advised routine use of those dishwasher-deep-clean detergents to stop the gunk from building up again.

Unfortunately despite using special cleaner every couple of months, and being more rigorous about pre-wash plate-scraping, the was has got quite bad again. (Yes, the spray arms are clean!)

So – two queries:

1. Are all deep-clean agents equal? Eg, I’ve been using these tablets from Sainsbury’s, at 26p per clean:
http://tinyurl.com/3emtbd

However, I recently saw this Special Stuff by Hagesan in a local hardware shop at 6 quid a go:
http://tinyurl.com/455xom

Is this stuff snake oil, or is it worth a pop?!

2. I find that the water in the sump at the end of the wash (on both sides if the mesh filter) is without fail very dirty. Presumably that’s what’s just been used in the final rinse cycle, isn’t it? Eeeugh. Shouldn’t this water be pretty much completely clean? Is this symptomatic of my problem?

Thanks for any advice.