Stickers are gummed and printed paper labels. The simpler the sticker the easier to reproduce with embossed and special shaped labels being harder to reproduce but not impossible. Labels made before, say arbitrarily, 1950 will be harder to reproduce due to the paper ands printing methods used, by the 1980's many were being made with plasticised materials that are easy to distinguish from older types.
But as with signatures, labels are easily added and are just another indicator of provenance. Ultimately you need a match on design, materials, manufacturing methods including finishing, in addition to labels and signatures. Most of the problems are encountered with the gift trade articles and it has been common practise since the souvenir trade began to produce these at the lowest possible price. I was always amused as a child to read the "Made in Hong Kong" or "Foreign" on the seaside souvenirs of Southend-On-Sea. Nothings changed but some still find it hard to accept.
Paul Ysart's earlier production of paperweights were made in difficult circumstances because of the intolerance of Salvador Ysart who regarded them as a complete waste of time, an attitude unchanged at Vasart. They did however have a good market, via Pirelli Glass, for these 'gift trade' baubles, the women could assemble the canes and the men could finish them off quickly resulting in very cheap items for resale... allowing the production of the important non-weight production to continue. No real art involved, yet some very attractive weights were also being made, no doubt because they did produce valuable cashflow. The abstract weights that were made at Strathearn and Caithness, Selkirk etc were also targetting the gift trade - being much easier and cheaper to make than millefiori. It is arbitrary who made the lampwork in PY weights as the concept of 'designer' weights did not really exist everything was the output of a chair - arguably until the 1990's when designers were being acknowledged in Caithness catalogues.
In 1989 John Deacons wrote "The few better quality weights I make are for collectors who phone or visit me. My main market is in the cheaper millefiori paperweights which I make in quantity. The workshop which I operate at present gives me a reasonable income producing paperweights which do not give production problems. I intend to continue this type of operation, gradually improving equipment etc. and perhaps producing a few more ‘specials’." http://www.ysartglass.com/Ysartnews/YsartnewsSpecial.htm#Deacons
In 2007, his studio is now one of the most important in Scotland, and longest surviving!
Memories are short and for those collecting paperweights in the last ten years would do well to look at the past history of collecting. Note also how the calibre of information has improved, often well referenced and approaching academic standards, although some still write with no acknowledgements to their sources they are more likely to be ignored.
In the 1980's Paul Ysart weights were nearly all in the USA and most of his unsigned pieces unrecognised or assumed to be antique (Bergstom collection). All 1848 weights were Whitefriars, now none are. It was collector groups in the USA, Germany and UK that started to change the culture and knowledge base through the 1970's and 1980's. As each area has been more extensively researched so more unrecognised weights are known as such and the process of ferreting out who made them continues. The growth of the Chinese gift trade weights has raised hackles but it has also started to fill in another area of unknown. A never ending process. Now we know Murano stickers are available in Vienna too