It seems the reason these things are such hang ups for Messianics and SDA's is because they have not been able to look beyond the letter of the Law to the Spirit of the Law.
For instance the OT law states that an Israelite may not touch the carcass of any unclean animal.
Lev 5:2 Or if a soul touch any unclean thing, whether [it be] a carcase of an unclean beast, or a carcase of unclean cattle, or the carcase of unclean creeping things, and [if] it be hidden from him; he also shall be unclean, and guilty.
But also commands the use of blue and purple all throughout the Law.
http://www.blueletterbible.org/search/translationResults.cfm?Criteria=blue&t=KJVHow do you think this dye was made? Snails.
As dye in Judaism
Some wool dipped in tekhelet solution, from the Hexaplex trunculus, turning blue in the sunlight outside P'til Tekhelet in Israel.The Hebrew Bible mentions a specific blue dye, called Tekhelet (Hebrew:
, pronounced [t???ele?]) for use in the Priestly garments as well in the layman's tzitzit, the formal tassels or fringes of clothing, which some believe refers to the indigo dye from the Hexaplex trunculus when kept in the sun.[2]
Similarly, the Hebrew Bible also mentions a specific purple dye, called argaman (Hebrew:
?? [?a??o?mon]), which refers to the purple color this same dye produces when kept in the shade.
That is, research by Otto Elsner (Shenker College of Fibers, Ramat Gan, Israel) and Ehud Spaneir (Haifa University, Haifa, Israel) showed that by performing what is commonly referred to as "vat dyeing" based on the dyestuff from the trunculus, they could achieve colors varying from blue to purple depending on exposure to the sun when the dye solution was in its leuco (reduced) state. This phenomenon was attributed to the dyestuff being composed of indigo, mono-bromo-indigo and di-bromo-indigo.[citation needed] DiBromo-Indigo presents itself as purple whereas Indigo is blue. It was demonstrated that when the reduced solution of trunculus dye is exposed to sunlight, the UV-rays from the sun act to break the bromine bonds such that when oxidation occurs following the removal of the dyed fabric from the solution, pure indigo bonds to the wool, while the bromine atoms are left in the vat.
This feature of final color varying according to exposure to the sun was indeed known by the ancients, as noted in the writings of Vitruvius (1 c. BCE), “Purple exceeds all colors in costliness and superiority of its delightful effect. It is obtained from a marine shellfish. ...It has not the same shade in all the places where it is found, but is naturally qualified by the course of the sun”.[3]
What is fascinating about that? Only that snails aren't clean by biblical standards. So either someone was confused here, though I doubt it, or God understood there is meaning behind the letter of the law. Something Jesus understood and expounded upon.
Mar 7:15 There is nothing from without a man, that entering into him can defile him: but the things which come out of him, those are they that defile the man