These are no massages. I went to a few of them before with my japanese friends. they are karaokes on thaniya street in silom. and its true many won't let farang or non-japanese in without the companionship of japanese customers.
And the total boom boom charge is outrageously high. you have to pay a high bar fine like 700-1500 bahts depend on the stores to take out the girl then negociate the babes for body fees somewhere like 2500-5000 or over. ask the girl everything before take her out. some girls will not boom boom at all.
These places are mostly catered to japanese businessmen for drinking and sex. many of them do not welcome non-jp customers because the stores know they are not the spenders like japanese.