Soap water for stickers?

[Tampan]

I have a set of WP shock stickers and the instructions call for the use of a soap water solution to be used on both the sticker, as well as the surface that it will be stuck on.
Is this normal practice for stickers? I would've thought that the soap would stuff up the glue on the sticker?

 

[meteldog]

 

[Lazybones]

 

[Tampan]

 

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[bud500 (R.I.P)]

 

[CycleC]

 

[2StrokeDan]