^if it was cut with caffeine tablets, say, that would be easy - just a cost factor compared with cut with glucose powder or somesuch. The trick from the seller's POV is to use a cut that allows the final product to be smoked, but with the same purity of (non-smokeable) powdered speed (say 10% meth, 90% cut); as long as this increases buyer demand, and hence selling price/profits.
Actually, I wonder if someone has just tried the pseudo- to meth conversion without bothering to remove the binders etc from the original cold tablets. The final result then would probably be smokable, and you've got your cut already in place (speed equivalent of tar heroin?!).
If you get a gluggy mix when you add water - this is definitely what happens when you try & shoot pills. USE COLD WATER - the meth will dissolve easily and the other crap will be easier to filter out. Use a pill filter if you can get them (5 micron or below) - that will get rid of the pill binders for sure.