ASP.NET Bundles how to disable minification

Conditional compilation directives are your friend:

#if DEBUG
            var jsBundle = new Bundle("~/Scripts/js");
#else
            var jsBundle = new ScriptBundle("~/Scripts/js");
#endif

If you have debug="true" in web.config and are using Scripts/Styles.Render to reference the bundles in your pages, that should turn off both bundling and minification. BundleTable.EnableOptimizations = false will always turn off both bundling and minification as well (irrespective of the debug true/false flag).

Are you perhaps not using the Scripts/Styles.Render helpers? If you are directly rendering references to the bundle via BundleTable.Bundles.ResolveBundleUrl() you will always get the minified/bundled content.