When do old Mercs become safe to buy?

[Sparta VAG]

Been engaged in my regular idle trawl through E-bay and noticing how many C/E Class Mercs there are at bargain prices. A few have caught my eye but I'm aware of the potential for rust/rot/electrical nightmares.

When's the generally agreed cut-off date for before these problems started? Is anything pre-1998 ok, or do I need to go back earlier?

[Strawman]

The switch to water based paints was around 1994, but cars from later than that can be alright in terms of rust, any car that has survived 10 years of UK roads will either be showing signs of rust or not by now. Electrical not sure but sort of 200-2005 they admitted recently they tried to introduce too many new innovations at once and dropped the ball in terms of their traditional reliability. You have to take each model on it's known merits/weaknesses I think.

[SuperHangOn]

There is no 'safe' year when looking at 15yo+ cars! A nice well looked after W210 will be better than a W124 which hasn't had an oil change in the last decade. You pays your money.

[Sparta VAG]

SuperHangOn said:

There is no 'safe' year when looking at 15yo+ cars! A nice well looked after W210 will be better than a W124 which hasn't had an oil change in the last decade. You pays your money.

I shouldn't have used the word "safe", I was thinking more specifically about when the rust-bork era began for Mercedes but consensus seems to be mid-late 90s

[Deva Link]

If you wanted something 'newer' the W203 C Class, especially after the mid-2004 facelift until it was replaced by W204, seems generally regarded as pretty bullet-proof.
(Declaration - I have a late 2004 C270CDi estate. I'm not a Merc fan-boy, it was just the right car to buy at the time).