First time change the Glow plugs on a warm engine. Took about 50 minutes after removal of the covers.

Attached is a picture is it normal for the body to be this clean on the removed plugs? The car has 98k miles.

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06 MB E320 CDI 123k miles
14 Sienna (wife's DD) 36k miles
11 GL350 Bluetec 136k (Sold)
96 E300; 292k+ miles (Donated)
11 Sprinter 22K+ miles (Sold)

Looks normal. Mine came with six original still working plugs that PO pulled at 113k miles just because he wanted to install new ones. Look just like yours.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 178k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 75k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I presume it is safe bet to think unlike OM606; the OM648 are not susceptible to carbon build up and getting stuck.

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06 MB E320 CDI 123k miles
14 Sienna (wife's DD) 36k miles
11 GL350 Bluetec 136k (Sold)
96 E300; 292k+ miles (Donated)
11 Sprinter 22K+ miles (Sold)

Maybe because in a CDI the glow plug tip isn’t stewing in a dense fuel mixture as it does in a prechamber.

Sixto
98 E320s sedan and wagon